diff --git a/.github/workflows/test-accessibility-alt-text-bot.yml b/.github/workflows/test-accessibility-alt-text-bot.yml
index bb5d580..eff925f 100644
--- a/.github/workflows/test-accessibility-alt-text-bot.yml
+++ b/.github/workflows/test-accessibility-alt-text-bot.yml
@@ -8,6 +8,8 @@ on:
     types: [created, edited]
   discussion:
     types: [created, edited]
+  discussion_comment:
+    types: [created, edited]
 
 jobs:
   accessibility_alt_text_bot:
diff --git a/README.md b/README.md
index 5e3fdcc..719aaf5 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,8 @@ on:
     types: [created, edited]
   discussion:
     types: [created, edited]
+  discussion_comment:
+    types: [created, edited]
 
 permissions:
   issues: write
diff --git a/action.yml b/action.yml
index 072d799..e2c6757 100644
--- a/action.yml
+++ b/action.yml
@@ -9,15 +9,26 @@ runs:
     - name: Runs alt text check and adds comment
       run: |
           source ${{ github.action_path }}/flag-alt-text.sh
+          source ${{ github.action_path }}/queries.sh
 
           if [ ${{ github.event.comment }} ]; then
             content=$COMMENT
-            issue_url=${{ github.event.issue.html_url }}
             user=${{ github.event.comment.user.login }}
             if ${{ github.event.issue.pull_request.url != '' }}; then
               type=pr_comment
+              issue_url=${{ github.event.issue.html_url }}
+            elif ${{ github.event.discussion.id != '' }}; then
+              type=discussion_comment
+              discussion_node_id='${{ github.event.discussion.node_id }}'
+              comment_node_id='${{ github.event.comment.node_id }}'
+              if ${{ github.event.comment.parent_id != '' }}; then
+                reply_to_id=$(getDiscussionReplyToId $comment_node_id)
+              else
+                reply_to_id=$comment_node_id
+              fi
             else
               type=issue_comment
+              issue_url=${{ github.event.issue.html_url }}
             fi
             target=${{ github.event.comment.html_url }}
           else
@@ -57,15 +68,9 @@ runs:
             elif [[ $type = issue_comment ]] || [[ $type = issue_description ]]; then
               gh issue comment $issue_url --body "$message"
             elif [[ $type = discussion_description ]]; then
-              gh api graphql -F discussionId="$discussion_node_id" -F body="$message" -f query='
-                mutation($discussionId: ID!, $body: String!) {
-                  addDiscussionComment(input: {discussionId: $discussionId, body: $body}) {
-                    comment {
-                      id
-                    }
-                  }
-                }
-              '
+              addDiscussionComment $discussion_node_id "$message"
+            elif [[ $type = discussion_comment ]]; then
+              addDiscussionComment $discussion_node_id "$message" $reply_to_id 
             fi
           fi
       shell: bash
diff --git a/queries.sh b/queries.sh
new file mode 100644
index 0000000..bd6b7d0
--- /dev/null
+++ b/queries.sh
@@ -0,0 +1,46 @@
+#!/bin/bash
+
+# Given a node_id for a discussion comment that is a reply in thread, return the parent comment's node ID.
+function getDiscussionReplyToId() {
+  local NODE_ID=$1
+  local REPLY_TO_DATA=$(gh api graphql -f query='
+  query($nodeId: ID!) {
+    node(id: $nodeId) {
+      ... on DiscussionComment {
+        replyTo {
+          id
+        }
+      }
+    }
+  }' -F nodeId=$NODE_ID)
+  echo $REPLY_TO_DATA | jq -r '.data.node.replyTo.id'
+}
+
+# Given a discussion node ID, a message, and an optional reply to node ID, adds a discussion comment.
+function addDiscussionComment() {
+  local DISCUSSION_NODE_ID=$1
+  local MESSAGE=$2
+  local REPLY_TO_ID=$3
+
+  if [ -n "$REPLY_TO_ID" ]; then
+    gh api graphql -F discussionId="$DISCUSSION_NODE_ID" -F replyToId="$REPLY_TO_ID" -F body="$MESSAGE" -f query='
+      mutation($discussionId: ID!, $replyToId: ID, $body: String!) {
+          addDiscussionComment(input: {discussionId: $discussionId, replyToId: $replyToId, body: $body}) {
+          comment {
+              id
+          }
+        }
+      }
+    '
+  else
+    gh api graphql -F discussionId="$discussion_node_id" -F body="$message" -f query='
+      mutation($discussionId: ID!, $body: String!) {
+        addDiscussionComment(input: {discussionId: $discussionId, body: $body}) {
+          comment {
+            id
+          }
+        }
+      }
+    '
+  fi
+}