diff --git a/CHANGELOG.md b/CHANGELOG.md
index 28fc76e..b5d742c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,31 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.3.0](https://github.com/elixir-telemetry/telemetry/tree/v0.3.0)
+
+This release marks the conversion from Elixir to Erlang. This is a breaking change, but the benefits
+largely surpass the drawbacks - Telemetry core can now be used by all projects running on the BEAM,
+regardless of the language they're written in.
+
+### Added
+
+* Added `:telemetry.handler/0`, `:telemetry.handler_function/0` and `:telemetry.handler_config/0`
+  types.
+
+### Changed
+
+* The library has been rewritten to Erlang. In Elixir, `:telemetry` module has to be used in place
+  of `Telemetry`. In Erlang, `telemetry` module has to be used in place of `'Elixir.Telemetry'`;
+* `:telemetry.list_handlers/1` returns a list of maps (of type `:telemetry.handler/0`) instead of
+  a list of tuples;
+* `:telemetry.attach/4` and `:telemetry.attach_many/4` replaced the 5-arity versions and now accept
+  an anonymous function for the handler function instead of a module and function name.
+
+### Removed
+
+* Removed `:telemetry.attach/5` and `:telemetry.attach_many/5` - 4-arity versions need to be used
+  now instead.
+
 ## [0.2.0](https://github.com/elixir-telemetry/telemetry/tree/v0.2.0)
 
 The main point of this release is to mark base Telemetry API as stable, so that other libraries can
diff --git a/doc/overview.edoc b/doc/overview.edoc
index 6c4bc28..60811b2 100644
--- a/doc/overview.edoc
+++ b/doc/overview.edoc
@@ -1,5 +1,5 @@
 @copyright 2018 Chris McCord and Erlang Solutions
-@version 0.2.0
+@version 0.3.0
 @title Telemetry
 @doc Telemetry is a dynamic dispatching library for metrics and instrumentations.
 It is lightweight, small and can be used in any Erlang or Elixir project.
diff --git a/rebar.config b/rebar.config
index c72c777..30c4f66 100644
--- a/rebar.config
+++ b/rebar.config
@@ -1,8 +1,20 @@
 {erl_opts, [debug_info]}.
 {deps, []}.
 
-{profiles, [{test, [{erl_opts, [nowarn_export_all]}]},
-            {docs, [{edoc_opts, [{preprocess, true}]}]}]}.
+{profiles, [
+    {test, [{erl_opts, [nowarn_export_all]},
+            %% create junit xml for circleci
+            {ct_opts, [{ct_hooks, [cth_surefire]}]},
+            {cover_enabled, true},
+            {cover_opts, [verbose]},
+            %% convert to data codecov understands
+            {project_plugins, [covertool]},
+            {covertool, [{coverdata_files, ["ct.coverdata"]}]}
+    ]},
+    {docs, [{edoc_opts, [{preprocess, true},
+                         {title, "Telemetry v0.3.0"}]}
+    ]}
+]}.
 
 {shell, [{apps, [telemetry]}]}.
 
@@ -10,16 +22,4 @@
 {xref_checks,[undefined_function_calls, undefined_functions, locals_not_used,
               deprecated_function_calls, deprecated_functions]}.
 
-%% set the title for generated docs
-{edoc_opts, [{title, "Telemetry v0.2.0"}]}.
-
-%% create junit xml for circleci
-{ct_opts, [{ct_hooks, [cth_surefire]}]}.
-
-{cover_enabled, true}.
-{cover_opts, [verbose]}.
-
-%% convert to data codecov understands
-{project_plugins, [covertool]}.
-{covertool, [{coverdata_files, ["ct.coverdata"]}]}.