diff --git a/README.md b/README.md
index 529e581..838a9f9 100644
--- a/README.md
+++ b/README.md
@@ -70,6 +70,37 @@ Check out the README within the sass directory for more information.
 Gesso includes several theme-specific settings for managing classes output by
 Drupal, which you can change at admin/appearance/settings/gesso.
 
+### Non-Drupal configuration files
+
+* config.rb: Ruby configuration file used for Compass compilation of Sass
+files.
+
+* Gemfile: Used by Bundler. Running `bundle install` will install the
+correct versions of all required dependencies.
+
+* Gemfile.lock: Generated by Bundler after running `bundle install`. Lists
+the exact versions installed, according to the minimum requirements set in the
+Gemfile.
+
+### Sass dependencies
+
+[Bundler](http://bundler.io) is used to manage the following dependencies and
+minimum required Ruby Gem versions. (Similar to [Bower](http://bower.io/), but
+for Ruby Gems.) To learn more about installing Bundler and compiling Sass, check
+out README.md within the sass directory.
+
+* [Breakpoint](http://breakpoint-sass.com): Easy to write media queries.
+
+* [Compass](http://compass-style.org): Open-source Sass framework.
+
+* [Sass](http://sass-lang.com): CSS on steroids. Adds nested rules, variables,
+mixins, selector inheritance, and more.
+
+* [Sass Globbing](https://github.com/chriseppstein/sass-globbing): Adds glob-
+based imports to Sass.
+
+* [Singularity](http://singularity.gs): Grid-based layout system.
+
 
 ## Maintainers