diff --git a/source/whats-new.txt b/source/whats-new.txt
index 420fd640..49bc54c3 100644
--- a/source/whats-new.txt
+++ b/source/whats-new.txt
@@ -22,14 +22,109 @@ following versions of the {+php-library+}:
 
 * :ref:`Version 1.20 <php-lib-version-1.20>`
 
+* :ref:`Version 1.18 <php-lib-version-1.18>`
+
+* :ref:`Version 1.17 <php-lib-version-1.17>`
+
+* :ref:`Version 1.16 <php-lib-version-1.16>`
+
+* :ref:`Version 1.15 <php-lib-version-1.15>`
+
 .. _php-lib-version-1.20:
 
 What's New in 1.20
 ------------------
 
-.. important:: MongoDB Server v3.6 End-of-Life
+.. important:: {+mdb-server+} v3.6 End-of-Life
 
-   Support for MongoDB Server v3.6 is removed in this release of the
+   Support for {+mdb-server+} v3.6 is removed in this release of the
    library.
 
-- Adds support for MongoDB Server v8.0.
\ No newline at end of file
+- Adds support for {+mdb-server+} v8.0.
+
+.. _php-lib-version-1.18:
+
+What's New in 1.18
+------------------
+
+- Adds a new GridFS API to make it more convenient to work with files using PHP's 
+  existing filesystem functions. The :phpmethod:`MongoDB\GridFS\Bucket::registerGlobalStreamWrapperAlias()` 
+  method may be used to register a global alias for a GridFS bucket. After 
+  doing so, files within that bucket can be accessed by using only a file URI 
+  (e.g. "gridfs://mybucket/hello.txt"). A demonstration of this API can be found
+  in the `gridfs_stream_wrapper.php <https://github.com/mongodb/mongo-php-library/blob/1.18.0/examples/gridfs_stream_wrapper.php>`__ 
+  example script.
+
+- Adds :phpmethod:`MongoDB\Client::addSubscriber()` and 
+  :phpmethod:`MongoDB\Client::removeSubscriber()` methods to the 
+  ``MongoDB\Client`` class to make it easier to register monitoring classes 
+  scoped to the underlying ``MongoDB\Driver\Manager`` object.
+
+To learn more about this release, see the `v1.18 Release Notes 
+<https://github.com/mongodb/mongo-php-library/releases/tag/1.18.0>`__ on GitHub.
+
+.. _php-lib-version-1.17:
+
+What's New in 1.17
+------------------
+
+- Introduces a new "codec" API for converting BSON to and from PHP objects. 
+  More information on this feature may be found in the 
+  :ref:`Codecs tutorial <php-codecs>`.
+
+- Adds :phpmethod:`MongoDB\add_logger()` and 
+  :phpmethod:`MongoDB\remove_logger()` functions to the library. 
+  These functions allow applications to register a `PSR-3 Logger <https://www.php-fig.org/psr/psr-3/>`__
+  to receive log messages emitted by the driver. Previously, logs were only 
+  available through the extension's `mongodb.debug <https://www.php.net/manual/en/mongodb.configuration.php#ini.mongodb.debug>`__ 
+  ``INI`` setting.
+
+- Introduces new :phpclass:`MongoDB\Collection` methods to create and manage 
+  Atlas Search indexes. Atlas Search indexes can be queried using the ``$search`` 
+  aggregation pipeline stage, which is supported in all versions of the library.
+  To learn more about Atlas Search indexes and the specifics of the ``$search`` 
+  aggregation stage, see the :atlas:`Atlas Search indexes </atlas-search>` 
+  documentation and :manual:`$search </reference/operator/aggregation/search/>`.
+
+- Upgrades the ``mongodb`` extension requirement to 1.17.0. Support for PHP 
+  7.2 and 7.3 has been removed and the library now requires PHP 7.4 or newer.
+
+To learn more about this release, see the `v1.17 Release Notes 
+<https://github.com/mongodb/mongo-php-library/releases/tag/1.17.0>`__ on GitHub.
+
+.. _php-lib-version-1.16:
+
+What's New in 1.16
+------------------
+
+- Introduces support for :v7.0:`MongoDB 7.0 </release-notes/7.0>`. 
+
+- Introduces :phpmethod:`MongoDB\Database::createEncryptedCollection()`. 
+  This method automatically creates data encryption keys when creating a new 
+  encrypted collection.
+
+- Upgrades the ``mongodb`` extension requirement to 1.16.0.
+
+To learn more about this release, see the `v1.16 Release Notes 
+<https://github.com/mongodb/mongo-php-library/releases/tag/1.16.0>`__ on GitHub.
+
+.. _php-lib-version-1.15:
+
+What's New in 1.15
+------------------
+
+- Adds new ``examples/`` and ``tools/`` directories to the library repository, 
+  which contain code snippets and scripts that may prove useful when writing 
+  or debugging applications. These directories are intended to 
+  supplement the library's existing documentation and will be added to over time.
+
+- Adds various backwards compatible typing improvements throughout the
+  library. Downstream impact for these changes are discussed in 
+  `UPGRADE-1.15.md <https://github.com/mongodb/mongo-php-library/blob/1.15.0/UPGRADE-1.15.md>`__. 
+  
+- Integrates `Psalm <https://psalm.dev/>`__ for static analysis.
+
+- Upgrades the ``mongodb`` extension requirement to 1.15.0.
+
+To learn more about this release, see the `v1.15 Release Notes 
+<https://github.com/mongodb/mongo-php-library/releases/tag/1.15.0>`__ on GitHub.