diff --git a/CHANGELOG.md b/CHANGELOG.md
index ecc1d287c1..4e78847c45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,43 @@
+0.20.0 (2023-09-29)
+===
+
+## What's Changed
+
+### Plan
+* Refactor derive macros and add HasSpaces trait by @wks in https://github.com/mmtk/mmtk-core/pull/934
+* Make MarkCompact LOS support 2nd transitive closure by @wenyuzhao in https://github.com/mmtk/mmtk-core/pull/944
+* Disabling PrepareMutator from PlanConstraints by @wks in https://github.com/mmtk/mmtk-core/pull/964
+
+### Policy
+* Add ExternalPageResource and allow discontiguous VM space by @qinsoon in https://github.com/mmtk/mmtk-core/pull/864
+* Discontiguous mark compact space support by @wenyuzhao in https://github.com/mmtk/mmtk-core/pull/939
+* Discontiguous PageProtect GC support  by @wenyuzhao in https://github.com/mmtk/mmtk-core/pull/946
+* Fix vo-bit reset for discontiguous space by @wenyuzhao in https://github.com/mmtk/mmtk-core/pull/948
+
+### API
+* Boot-time configurable heap constants by @wenyuzhao in https://github.com/mmtk/mmtk-core/pull/899
+* This PR enables transitively pinning (TP) objects from particular roots for Immix/StickyImmix by @udesou in https://github.com/mmtk/mmtk-core/pull/897
+* Let VM control when or if to read env var options by @wks in https://github.com/mmtk/mmtk-core/pull/955
+
+### Misc
+* Update doc comment of Scanning::process_weak_refs by @wks in https://github.com/mmtk/mmtk-core/pull/919
+* Binding test for Ruby by @wks in https://github.com/mmtk/mmtk-core/pull/916
+* Fix api-check CI by @wks in https://github.com/mmtk/mmtk-core/pull/923
+* Fix default value for RUBY_BINDING_REPO by @qinsoon in https://github.com/mmtk/mmtk-core/pull/926
+* Add a ready-to-merge check by @qinsoon in https://github.com/mmtk/mmtk-core/pull/910
+* Run ready to merge check for PRs by @qinsoon in https://github.com/mmtk/mmtk-core/pull/928
+* Remove cast ref to mut everywhere by @playXE in https://github.com/mmtk/mmtk-core/pull/893
+* Benchmark Rust code by @qinsoon in https://github.com/mmtk/mmtk-core/pull/933
+* Fix broken links in the tutorial by @caizixian in https://github.com/mmtk/mmtk-core/pull/936
+* Update doc to add a section for LTO by @qinsoon in https://github.com/mmtk/mmtk-core/pull/937
+* Add CARGO_INCREMENTAL=0 to work around clippy 1.72 bug by @qinsoon in https://github.com/mmtk/mmtk-core/pull/938
+* Fix issues for cargo fmt in 1.72 by @qinsoon in https://github.com/mmtk/mmtk-core/pull/940
+* Use atomic operations for SFT map and remove unsafe code by @qinsoon in https://github.com/mmtk/mmtk-core/pull/931
+* Fix outdated Rust version in README by @qinsoon in https://github.com/mmtk/mmtk-core/pull/942
+* Fix length of Map64::descriptor_map by @wks in https://github.com/mmtk/mmtk-core/pull/956
+
+**Full Changelog**: https://github.com/mmtk/mmtk-core/compare/v0.19.0...v0.20.0
+
 0.19.0 (2023-08-18)
 ===
 
@@ -76,6 +116,7 @@
 * @ClSlaid made their first contribution in https://github.com/mmtk/mmtk-core/pull/843
 * @playXE made their first contribution in https://github.com/mmtk/mmtk-core/pull/880
 
+
 **Full Changelog**: https://github.com/mmtk/mmtk-core/compare/v0.18.0...v0.19.0
 
 0.18.0 (2023-04-03)
diff --git a/Cargo.toml b/Cargo.toml
index ca172f6a81..b5d5dfc621 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mmtk"
-version = "0.19.0"
+version = "0.20.0"
 authors = ["The MMTk Developers <>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"
@@ -37,7 +37,7 @@ log = { version = "0.4", features = ["max_level_trace", "release_max_level_off"]
 memoffset = "0.9"
 mimalloc-sys = { version = "0.1.6", optional = true }
 # MMTk macros
-mmtk-macros = { version = "0.19.0", path = "macros/" }
+mmtk-macros = { version = "0.20.0", path = "macros/" }
 num_cpus = "1.8"
 num-traits = "0.2"
 pfm = { version = "0.1.0-beta.3", optional = true }
diff --git a/macros/Cargo.toml b/macros/Cargo.toml
index 9928c78563..2301e71b2e 100644
--- a/macros/Cargo.toml
+++ b/macros/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "mmtk-macros"
 # the macro crate uses the same version as mmtk-core
-version = "0.19.0"
+version = "0.20.0"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 description = "MMTk macros provides procedural macros used by mmtk-core."