diff --git a/CHANGELOG.md b/CHANGELOG.md
index df35bef..1b21e9f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,36 @@ This project uses [**Break Versioning**](https://www.taoensso.com/break-versioni
 
 ---
 
+# `v6.6.0-RC1` (2024-08-30)
+
+📦 **Available on Clojars**: [Timbre](https://clojars.org/com.taoensso/timbre/versions/6.6.0-RC1) | [SLF4J provider](https://clojars.org/com.taoensso/timbre-slf4j/versions/6.6.0-RC1)  
+Uses [Break Versioning](https://www.taoensso.com/break-versioning).
+
+---
+
+This is a significant **feature** release that includes new **built-in support** for [Java logging interop via SLF4J](https://github.com/taoensso/timbre/wiki/4-Interop#java-logging).
+
+Big thanks to @fzakaria for their long-time work on Timbre's [previous optional SLF4J interop](https://github.com/fzakaria/slf4j-timbre) 🙏
+
+As always, feedback and bug reports very welcome! - [Peter Taoussanis](https://www.taoensso.com)
+
+## Changes since `v6.5.0` (2024-02-26)
+
+* 6d7495a7 [mod] `default-output-fn`: omit "?" location info
+
+## New since `v6.5.0` (2024-02-26)
+
+* 6b4873ec [new] Add SLF4Jv2 backend/provider
+* 95ea032d [new] [#389] Capture cause of failing error-fn
+* 0fa226eb [doc] [#386] Add `timbre-json-appender` to wiki (@NoahTheDuke)
+* Various internal improvements and updated dependencies
+
+## Fixes since `v6.5.0` (2024-02-26)
+
+* None
+
+---
+
 # `v6.5.0` (2024-02-26)
 
 > 📦 [Available on Clojars](https://clojars.org/com.taoensso/timbre/versions/6.5.0), this project uses [Break Versioning](https://www.taoensso.com/break-versioning).
diff --git a/README.md b/README.md
index 0182fcc..fffadb7 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,7 @@ There's **zero pressure** for existing users of Timbre to migrate, though there
 
 ## Latest release/s
 
+- `2024-08-30` `v6.6.0-RC1` (next): [release info](../../releases/tag/v6.6.0-RC1)
 - `2024-02-26` `v6.5.0` (stable): [release info](../../releases/tag/v6.5.0)
 
 [![Main tests][Main tests SVG]][Main tests URL]
diff --git a/project.clj b/project.clj
index d1a3fdb..8bc547e 100644
--- a/project.clj
+++ b/project.clj
@@ -1,4 +1,4 @@
-(defproject com.taoensso/timbre "6.6.0-SNAPSHOT"
+(defproject com.taoensso/timbre "6.6.0-RC1"
   :author "Peter Taoussanis <https://www.taoensso.com>"
   :description "Pure Clojure/Script logging library"
   :url "https://www.taoensso.com/timbre"
@@ -67,7 +67,7 @@
     [[org.clojure/test.check    "1.1.1"]
      [org.clojure/tools.logging "1.3.0"]
      [org.slf4j/slf4j-api       "2.0.16"]
-     [com.taoensso/timbre-slf4j "6.6.0-SNAPSHOT"]
+     [com.taoensso/timbre-slf4j "6.6.0-RC1"]
      [com.taoensso/nippy        "3.4.2"]
      [com.taoensso/carmine      "3.4.1" :exclusions [com.taoensso/timbre]]
      [com.draines/postal        "2.0.5"]]
diff --git a/slf4j/project.clj b/slf4j/project.clj
index a86f2b3..aead208 100644
--- a/slf4j/project.clj
+++ b/slf4j/project.clj
@@ -1,4 +1,4 @@
-(defproject com.taoensso/timbre-slf4j "6.6.0-SNAPSHOT"
+(defproject com.taoensso/timbre-slf4j "6.6.0-RC1"
   :author "Peter Taoussanis <https://www.taoensso.com>"
   :description "Timbre backend/provider for SLF4J API v2"
   :url "https://www.taoensso.com/timbre"
@@ -18,7 +18,7 @@
    {:dependencies
     [[org.clojure/clojure "1.11.4"]
      [org.slf4j/slf4j-api "2.0.16"]
-     [com.taoensso/timbre "6.6.0-SNAPSHOT"]]}
+     [com.taoensso/timbre "6.6.0-RC1"]]}
 
    :dev
    {:plugins