diff --git a/modules/README.txt b/modules/README.txt
index f4e35b5..bde5cbf 100644
--- a/modules/README.txt
+++ b/modules/README.txt
@@ -1,4 +1,18 @@
 
-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 beyond Drupal core. This encourages best practices
+and facilitates safe, self-contained code updates.
+
+It is safe to organize modules into subdirectories, such as "contrib" for
+contributed modules downloaded from Drupal.org, and "custom" for custom modules.
+Note that if you move a module to a subdirectory after it has been enabled, you
+may need to clear the Drupal cache so that it can be found.
+
+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 restrict 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..5cf84f1 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; this
+encourages best practices and facilitates safe, self-contained code updates.
+
+Install profiles define additional installation steps (such as enabling modules,
+defining content types, etc.) that run after the base installation from core
+when Drupal is first installed 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 a profile's availability to a
+specific site instance.
+
+Additionally, modules and themes may be placed inside subdirectories 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/sites/README.txt b/sites/README.txt
new file mode 100644
index 0000000..361370a
--- /dev/null
+++ b/sites/README.txt
@@ -0,0 +1,6 @@
+
+This directory structure contains the settings and configuration files specific
+to your site or sites and is an integral part of multisite configurations.
+
+See core/INSTALL.txt for information about single-site installation or
+multisite configuration.
diff --git a/themes/README.txt b/themes/README.txt
index e942521..e8d7961 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 modify
+the appearance of your site beyond Drupal core themes. This encourages best
+practices and facilitates safe, self-contained code updates. It is safe to
+organize themes into subdirectories 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.