diff --git a/modules/README.txt b/modules/README.txt
index f4e35b5..e99c2d1 100644
--- a/modules/README.txt
+++ b/modules/README.txt
@@ -1,4 +1,14 @@
 
-This directory should be used to place downloaded and custom modules
-which are common to all sites. This will allow you to more easily
-update Drupal core files.
+This directory should be used to keep downloaded and custom modules that extend
+your site's functionality separate from Drupal core, encouraging best practices
+and facilitating safer self-contained code updates. It is safe to organize
+modules into sub-directories.
+
+In multisite configuration, modules found in this directory are available to
+all sites. In addition to this directory, shared common modules may also be kept
+in the sites/all/modules directory and will take precedence over modules in this
+directory. Alternatively, the sites/your_site_name/modules directory pattern may
+be used to restricted modules to a specific site instance.
+
+Refer to the "Developing for Drupal" section of the README.txt in the Drupal
+root directory for further information on extending Drupal with custom modules.
diff --git a/profiles/README.txt b/profiles/README.txt
index 2bbf4c9..42a9c5d 100644
--- a/profiles/README.txt
+++ b/profiles/README.txt
@@ -1,4 +1,30 @@
 
-This directory should be used to place downloaded and custom profiles
-which are common to all sites. This will allow you to more easily
-update Drupal core files.
+This directory should be used to keep downloaded and custom installation
+profiles (a.k.a. install profiles) separate from Drupal core profiles,
+facilitating safer self-contained code updates.
+
+Install profiles define installation steps (such as enabling modules,
+defining content types, etc.) that run after Drupal's base installation when
+you first install Drupal and are what developers create as the basis of
+distributions.
+
+In multisite configuration, install profiles found in this directory are
+available to all sites during their initial site installation. For consistency
+with the similar /modules and /themes directories, shared common profiles may
+also be kept in the sites/all/profiles directory and will take precedence over
+profiles in this directory. Alternatively, the sites/your_site_name/profiles
+directory pattern may be used to restrict profiles availability to a specific
+site instance.
+
+Additionally, modules and themes may be placed inside sub-directories in a
+specific install profile such as profiles/your_site_profile/modules and
+profiles/your_site_profile/themes respectively to restrict their usage to only
+sites that were installed with that specific profile.
+
+More about install profiles and distributions:
+* Read about the difference between install profiles and distributions:
+  http://drupal.org/node/1089736.
+* Download contributed install profiles and distributions:
+  http://drupal.org/project/distributions
+* Develop your own install profile or distribution:
+  http://drupal.org/developing/distributions
diff --git a/themes/README.txt b/themes/README.txt
index e942521..d685bc8 100644
--- a/themes/README.txt
+++ b/themes/README.txt
@@ -1,4 +1,15 @@
 
-This directory should be used to place downloaded and custom themes
-which are common to all sites. This will allow you to more easily
-update Drupal core files.
+This directory should be used to keep downloaded and custom themes that improve
+the appearance of your site separate from Drupal core themes, encouraging best
+practices and facilitating safer self-contained code updates. It is safe to
+organize themes into sub-directories and is recommended to use Drupal's
+sub-theme functionality to ensure easy maintenance and upgrades.
+
+In multisite configuration, themes found in this directory are available to
+all sites. In addition to this directory, shared common themes may also be kept
+in the sites/all/themes directory and will take precedence over themes in this
+directory. Alternatively, the sites/your_site_name/themes directory pattern may
+be used to restrict themes to a specific site instance.
+
+Refer to the "Appearance" section of the README.txt in the Drupal root
+directory for further information on theming.