diff --git a/src/metldata/builtin_transformations/add_content_properties/assumptions.py b/src/metldata/builtin_transformations/add_content_properties/assumptions.py
new file mode 100644
index 0000000..a6732bd
--- /dev/null
+++ b/src/metldata/builtin_transformations/add_content_properties/assumptions.py
@@ -0,0 +1,57 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Check model assumptions for the add content properties transformation."""
+
+from schemapack.spec.schemapack import SchemaPack
+
+from metldata.builtin_transformations.add_content_properties.instruction import (
+    AddContentPropertyInstruction,
+)
+from metldata.builtin_transformations.add_content_properties.path import (
+    resolve_schema_object_path,
+)
+from metldata.transform.base import ModelAssumptionError
+
+
+def check_model_assumptions(
+    schema: SchemaPack,
+    instructions_by_class: dict[str, list[AddContentPropertyInstruction]],
+) -> None:
+    """Check the model assumptions for the add content properties transformation."""
+    for class_name, instructions in instructions_by_class.items():
+        class_def = schema.classes.get(class_name)
+
+        # Check if the class exists in the model
+        if not class_def:
+            raise ModelAssumptionError(
+                f"Class {class_name} does not exist in the model."
+            )
+
+        for instruction in instructions:
+            # Check if the property already exists in the target schema
+            try:
+                target_schema = resolve_schema_object_path(
+                    json_schema=class_def.content.json_schema_dict,
+                    path=instruction.target_content.object_path,
+                )
+            except KeyError:
+                continue
+            if instruction.target_content.property_name in target_schema.get(
+                "properties", {}
+            ):
+                raise ModelAssumptionError(
+                    f"Property {instruction.target_content.property_name} already exists"
+                    + f" in class {class_name}."
+                )
diff --git a/src/metldata/builtin_transformations/add_content_properties/config.py b/src/metldata/builtin_transformations/add_content_properties/config.py
new file mode 100644
index 0000000..5b0090f
--- /dev/null
+++ b/src/metldata/builtin_transformations/add_content_properties/config.py
@@ -0,0 +1,50 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""Models used to describe content properties that shall be deleted."""
+
+from pydantic import Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+from metldata.builtin_transformations.add_content_properties.instruction import (
+    AddContentPropertyInstruction,
+)
+
+
+class AddContentPropertiesConfig(BaseSettings):
+    """A Config for a transformation that adds a new property to an object within a
+    content schema
+    """
+
+    model_config = SettingsConfigDict(extra="forbid")
+
+    add_content_properties: list[AddContentPropertyInstruction] = Field(
+        ...,
+        description=(
+            "A list of instructions to add content properties to the model and data."
+        ),
+    )
+
+    def instructions_by_class(
+        self,
+    ) -> dict[str, list[AddContentPropertyInstruction]]:
+        """Returns a dictionary of instructions by class."""
+        instructions_by_class: dict[str, list[AddContentPropertyInstruction]] = {}
+        for instruction in self.add_content_properties:
+            instructions_by_class.setdefault(instruction.class_name, []).append(
+                instruction
+            )
+        return instructions_by_class
diff --git a/src/metldata/builtin_transformations/add_content_properties/data_transform.py b/src/metldata/builtin_transformations/add_content_properties/data_transform.py
new file mode 100644
index 0000000..9e23060
--- /dev/null
+++ b/src/metldata/builtin_transformations/add_content_properties/data_transform.py
@@ -0,0 +1,73 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Data transformation logic for the add content properties transformation."""
+
+from copy import deepcopy
+
+from schemapack.spec.datapack import DataPack
+
+from metldata.builtin_transformations.add_content_properties.instruction import (
+    AddContentPropertyInstruction,
+)
+from metldata.builtin_transformations.add_content_properties.path import (
+    resolve_data_object_path,
+)
+from metldata.transform.base import EvitableTransformationError
+
+
+def add_properties(
+    *,
+    data: DataPack,
+    instructions_by_class: dict[str, list[AddContentPropertyInstruction]],
+) -> DataPack:
+    """Given a data pack and a dictionary of instructions by class, add the specified
+    content properties to the data.
+
+    Args:
+        data:
+            The datapack to add the content properties to.
+        instructions_by_class:
+            A dictionary mapping class names to lists of instructions.
+
+    Returns:
+        The data with the specified content properties being added.
+    """
+    modified_data = data.model_copy(deep=True)
+
+    for class_name, instructions in instructions_by_class.items():
+        resources = modified_data.resources.get(class_name)
+
+        if not resources:
+            raise EvitableTransformationError()
+
+        for resource in resources.values():
+            for instruction in instructions:
+                content = resource.content
+                object = resolve_data_object_path(
+                    data=content,
+                    path=instruction.target_content.object_path,
+                )
+
+                if (
+                    not isinstance(object, dict)
+                    or instruction.target_content.property_name in object
+                ):
+                    raise EvitableTransformationError()
+
+                object[instruction.target_content.property_name] = deepcopy(
+                    instruction.value
+                )
+
+    return modified_data
diff --git a/src/metldata/builtin_transformations/add_content_properties/instruction.py b/src/metldata/builtin_transformations/add_content_properties/instruction.py
new file mode 100644
index 0000000..5b56771
--- /dev/null
+++ b/src/metldata/builtin_transformations/add_content_properties/instruction.py
@@ -0,0 +1,72 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Models for instructions used in the 'add content properties' transformation."""
+
+from typing import Any, Final
+
+from pydantic import Field
+from pydantic_settings import BaseSettings
+
+DEFAULT_CONTENT_SCHEMA: Final[dict[str, Any]] = {
+    "type": "object",
+    "additionalProperties": False,
+}
+
+
+class NewContentSchemaPath(BaseSettings):
+    """A model describing the path of an object property within the content schema that
+    is yet to be added. The model comprises a path to an already existing object within
+    the content schema and the name of a property to be added to that object's schema
+    """
+
+    object_path: str = Field(
+        ...,
+        description=(
+            "The path to the content object to which a property shall be added. The"
+            + " path must be specified in dot notation, equivalently to JavaScript"
+            + " property accessors."
+        ),
+        examples=["some_property.another_nested_property"],
+    )
+
+    property_name: str = Field(..., description="The name of the property to be added.")
+
+
+class AddContentPropertyInstruction(BaseSettings):
+    """A model describing an instruction to add a new content property to a class in a
+    schemapack, including an associated default value in corresponding data.
+    """
+
+    class_name: str = Field(..., description="The name of the class to modify.")
+
+    target_content: NewContentSchemaPath
+
+    required: bool = Field(
+        True,
+        description=(
+            "Indicates whether the newly added property shall be added to the"
+            + " 'required' list of the corresponding object. Defaults to 'True'."
+        ),
+    )
+
+    content_schema: dict[str, Any] = Field(
+        DEFAULT_CONTENT_SCHEMA,
+        description="The JSON schema of the newly added property.",
+    )
+
+    value: Any = Field(
+        {}, description="A value to assign to the new property in the data."
+    )
diff --git a/src/metldata/builtin_transformations/add_content_properties/main.py b/src/metldata/builtin_transformations/add_content_properties/main.py
new file mode 100644
index 0000000..a3150c8
--- /dev/null
+++ b/src/metldata/builtin_transformations/add_content_properties/main.py
@@ -0,0 +1,85 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""A transformation to add content properties."""
+
+from schemapack.spec.datapack import DataPack
+from schemapack.spec.schemapack import SchemaPack
+
+from metldata.builtin_transformations.add_content_properties.assumptions import (
+    check_model_assumptions,
+)
+from metldata.builtin_transformations.add_content_properties.config import (
+    AddContentPropertiesConfig,
+)
+from metldata.builtin_transformations.add_content_properties.data_transform import (
+    add_properties,
+)
+from metldata.builtin_transformations.add_content_properties.model_transform import (
+    add_content_properties,
+)
+from metldata.transform.base import (
+    DataTransformer,
+    TransformationDefinition,
+)
+
+
+class AddContentPropertiesTransformer(DataTransformer[AddContentPropertiesConfig]):
+    """A transformer that deletes content properties from data."""
+
+    def transform(self, data: DataPack) -> DataPack:
+        """Transforms data.
+
+        Args:
+            data: The data as DataPack to be transformed.
+        """
+        return add_properties(
+            data=data, instructions_by_class=self._config.instructions_by_class()
+        )
+
+
+def check_model_assumptions_wrapper(
+    model: SchemaPack,
+    config: AddContentPropertiesConfig,
+) -> None:
+    """Check the assumptions of the model.
+
+    Raises:
+        ModelAssumptionError:
+            if the model does not fulfill the assumptions.
+    """
+    check_model_assumptions(
+        schema=model, instructions_by_class=config.instructions_by_class()
+    )
+
+
+def transform_model(
+    model: SchemaPack, config: AddContentPropertiesConfig
+) -> SchemaPack:
+    """Transform the data model."""
+    return add_content_properties(
+        model=model, instructions_by_class=config.instructions_by_class()
+    )
+
+
+ADD_CONTENT_PROPERTIES_TRANSFORMATION = TransformationDefinition[
+    AddContentPropertiesConfig
+](
+    config_cls=AddContentPropertiesConfig,
+    check_model_assumptions=check_model_assumptions_wrapper,
+    transform_model=transform_model,
+    data_transformer_factory=AddContentPropertiesTransformer,
+)
diff --git a/src/metldata/builtin_transformations/add_content_properties/model_transform.py b/src/metldata/builtin_transformations/add_content_properties/model_transform.py
new file mode 100644
index 0000000..d0378be
--- /dev/null
+++ b/src/metldata/builtin_transformations/add_content_properties/model_transform.py
@@ -0,0 +1,76 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Model transformation logic for the 'add content property' transformation"""
+
+from copy import deepcopy
+
+from schemapack.spec.schemapack import (
+    ClassDefinition,
+    SchemaPack,
+)
+
+from metldata.builtin_transformations.add_content_properties.instruction import (
+    AddContentPropertyInstruction,
+)
+from metldata.builtin_transformations.add_content_properties.path import (
+    resolve_schema_object_path,
+)
+from metldata.transform.base import EvitableTransformationError
+
+
+def add_content_properties(
+    *,
+    model: SchemaPack,
+    instructions_by_class: dict[str, list[AddContentPropertyInstruction]],
+) -> SchemaPack:
+    """Adds a new content property to the provided model."""
+    updated_class_defs: dict[str, ClassDefinition] = {}
+    for class_name, cls_instructions in instructions_by_class.items():
+        class_def = model.classes.get(class_name)
+
+        if not class_def:
+            raise EvitableTransformationError()
+
+        content_schema = class_def.content.json_schema_dict
+
+        for cls_instruction in cls_instructions:
+            try:
+                target_object = resolve_schema_object_path(
+                    content_schema, cls_instruction.target_content.object_path
+                )
+            except KeyError as e:
+                raise EvitableTransformationError() from e
+
+            if cls_instruction.target_content.property_name in content_schema.get(
+                "properties", {}
+            ):
+                raise EvitableTransformationError()
+
+            target_object.setdefault("properties", {})[
+                cls_instruction.target_content.property_name
+            ] = deepcopy(cls_instruction.content_schema)
+
+            if cls_instruction.required:
+                target_object.setdefault("required", []).append(
+                    cls_instruction.target_content.property_name
+                )
+
+        updated_class_defs[class_name] = class_def.model_validate(
+            {**class_def.model_dump(), "content": content_schema}
+        )
+
+    model_dict = model.model_dump()
+    model_dict["classes"].update(updated_class_defs)
+    return SchemaPack.model_validate(model_dict)
diff --git a/src/metldata/builtin_transformations/add_content_properties/path.py b/src/metldata/builtin_transformations/add_content_properties/path.py
new file mode 100644
index 0000000..5f7acc7
--- /dev/null
+++ b/src/metldata/builtin_transformations/add_content_properties/path.py
@@ -0,0 +1,64 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Helper function for dot-separated strings describing property paths in JSON
+schemas.
+"""
+
+from collections.abc import Mapping
+from typing import Any
+
+
+def resolve_schema_object_path(json_schema: Mapping[str, Any], path: str) -> Any:
+    """Given a JSON schema describing an object, resolve the dot-separated path to a
+    property. Return the property schema.
+
+    Args:
+        json_schema:
+            The JSON schema of the object.
+        path:
+            The dot-separated path to the property.
+
+    Raises:
+        KeyError:
+            If the path does not exist in the schema.
+
+    Returns: The schema of the property at the given path.
+    """
+    if path:
+        for key in path.split("."):
+            json_schema = json_schema["properties"][key]
+    return json_schema
+
+
+def resolve_data_object_path(data: Mapping, path: str) -> Any:
+    """Given a mapping, resolve the dot-separated path to a property. Return the
+    property value.
+
+    Args:
+        data:
+            The JSON object.
+        path:
+            The dot-separated path to the property.
+
+    Raises:
+        KeyError:
+            If the path does not exist in the data.
+
+    Returns: The value of the property at the given path.
+    """
+    if path:
+        for key in path.split("."):
+            data = data[key]
+    return data
diff --git a/tests/fixtures/example_transformations/add_content_properties/multiple/config.yaml b/tests/fixtures/example_transformations/add_content_properties/multiple/config.yaml
new file mode 100644
index 0000000..ce4e87c
--- /dev/null
+++ b/tests/fixtures/example_transformations/add_content_properties/multiple/config.yaml
@@ -0,0 +1,22 @@
+add_content_properties:
+- class_name: File
+  target_content:
+    object_path: ""
+    property_name: "additional_information"
+  required: false
+- class_name: File
+  target_content:
+    object_path: "additional_information"
+    property_name: "compression"
+  content_schema:
+    type: "boolean"
+  value: false
+  # required is not set, so it defaults to false
+- class_name: File
+  target_content:
+    object_path: ""
+    property_name: "content_description"
+  content_schema:
+    type: "string"
+  required: true
+  value: ""
diff --git a/tests/fixtures/example_transformations/add_content_properties/multiple/transformed.datapack.yaml b/tests/fixtures/example_transformations/add_content_properties/multiple/transformed.datapack.yaml
new file mode 100644
index 0000000..4e110b6
--- /dev/null
+++ b/tests/fixtures/example_transformations/add_content_properties/multiple/transformed.datapack.yaml
@@ -0,0 +1,59 @@
+datapack: 0.3.0
+resources:
+  File:
+    file_a:
+      content:
+        filename: file_a.fastq
+        format: FASTQ
+        checksum: 1a5ac10ab42911dc0224172c118a326d9a4c03969112a2f3eb1ad971e96e92b8
+        size: 12321
+        additional_information: # <-
+          compression: false
+        content_description: "" # <-
+    file_b:
+      content:
+        filename: file_b.fastq
+        format: FASTQ
+        checksum: 2b5ac10ab42911dc0224172c118a326d9a4c03969112a2f3eb1ad971e96e92c9
+        size: 12314
+        additional_information: # <-
+          compression: false
+        content_description: "" # <-
+    file_c:
+      content:
+        filename: file_c.fastq
+        format: FASTQ
+        checksum: a9c24870071da03f78515e6197048f3a2172e90e597e9250cd01a0cb8f0986ed
+        size: 12123
+        additional_information: # <-
+          compression: false
+        content_description: "" # <-
+  Dataset:
+    dataset_1:
+      content:
+        dac_contact: dac@example.org
+      relations:
+        files:
+          - file_a
+          - file_b
+          - file_c
+  Sample:
+    sample_x:
+      content:
+        description: Some sample.
+      relations:
+        files:
+          - file_a
+          - file_b
+    sample_y:
+      content: {}
+      relations:
+        files:
+          - file_c
+  Experiment:
+    experiment_i:
+      content: {}
+      relations:
+        samples:
+          - sample_x
+          - sample_y
diff --git a/tests/fixtures/example_transformations/add_content_properties/multiple/transformed.schemapack.yaml b/tests/fixtures/example_transformations/add_content_properties/multiple/transformed.schemapack.yaml
new file mode 100644
index 0000000..2a9ada0
--- /dev/null
+++ b/tests/fixtures/example_transformations/add_content_properties/multiple/transformed.schemapack.yaml
@@ -0,0 +1,86 @@
+schemapack: 0.3.0
+classes:
+  File:
+    id:
+      propertyName: alias
+    content: {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "additionalProperties": false,
+      "description": "A file is an object that contains information generated from a process, either an Experiment or an Analysis.",
+      "properties": {
+        "checksum": {
+          "type": "string"
+        },
+        "filename": {
+          "type": "string"
+        },
+        "format": {
+          "type": "string"
+        },
+        "size": {
+          "type": "integer"
+        },
+        "additional_information": { # <-
+          "type": "object",
+          "additionalProperties": false,
+          "properties": {
+            "compression": {
+              "type": "boolean"
+            }
+          },
+          "required": [
+            "compression"
+          ],
+        },
+        "content_description": {
+          "type" : "string"
+        }
+      },
+      "required": [
+        "filename",
+        "format",
+        "checksum",
+        "size",
+        "content_description",
+      ],
+      "type": "object"
+    }
+  Dataset:
+    id:
+      propertyName: alias
+    content: ../../../example_content_schemas/Dataset.schema.json
+    relations:
+      files:
+        targetClass: File
+        multiple:
+          origin: true
+          target: true
+        mandatory:
+          origin: false
+          target: true
+  Sample:
+    id:
+      propertyName: alias
+    content: ../../../example_content_schemas/Sample.schema.json
+    relations:
+      files:
+        targetClass: File
+        multiple:
+          origin: false
+          target: true
+        mandatory:
+          origin: false
+          target: true
+  Experiment:
+    id:
+      propertyName: alias
+    content: ../../../example_content_schemas/Experiment.schema.json
+    relations:
+      samples:
+        targetClass: Sample
+        multiple:
+          origin: false
+          target: true
+        mandatory:
+          origin: true
+          target: true
diff --git a/tests/fixtures/transformations.py b/tests/fixtures/transformations.py
index ae56376..35e6e37 100644
--- a/tests/fixtures/transformations.py
+++ b/tests/fixtures/transformations.py
@@ -23,6 +23,9 @@
 from schemapack.spec.datapack import DataPack
 from schemapack.spec.schemapack import SchemaPack
 
+from metldata.builtin_transformations.add_content_properties.main import (
+    ADD_CONTENT_PROPERTIES_TRANSFORMATION,
+)
 from metldata.builtin_transformations.delete_properties.main import (
     PROPERTY_DELETION_TRANSFORMATION,
 )
@@ -39,6 +42,7 @@
 TRANSFORMATIONS_BY_NAME: dict[str, TransformationDefinition] = {
     "infer_relations": RELATION_INFERENCE_TRANSFORMATION,
     "delete_properties": PROPERTY_DELETION_TRANSFORMATION,
+    "add_content_properties": ADD_CONTENT_PROPERTIES_TRANSFORMATION,
 }