diff --git a/doc/rg.1 b/doc/rg.1
index 7b87ea40..1f29c8f0 100644
--- a/doc/rg.1
+++ b/doc/rg.1
@@ -397,9 +397,38 @@ inside of ripgrep.
 Note that this must be passed to every invocation of rg.
 Type settings are NOT persisted.
 .RS
+.IP
+.nf
+\f[C]
+\ \ Example:\ `rg\ \-\-type\-add\ \[aq]foo:*.foo\[aq]\ \-tfoo\ PATTERN`
+\f[]
+.fi
 .PP
-Example:
-\f[C]rg\ \-\-type\-add\ \[aq]foo:*.foo\[aq]\ \-tfoo\ PATTERN\f[]
+\-\-type\-add can also be used to include rules from other types with
+the special include directive.
+The include directive permits specifying one or more other type names
+(separated by a comma) that have been defined and its rules will
+automatically be imported into the type specified.
+For example, to create a type called src that matches C++, Python and
+Markdown files, one can use:
+.IP
+.nf
+\f[C]
+\ \ `\-\-type\-add\ \[aq]src:include:cpp,py,md\[aq]`
+\f[]
+.fi
+.PP
+Additional glob rules can still be added to the src type by using the
+\-\-type\-add flag again:
+.IP
+.nf
+\f[C]
+\ \ `\-\-type\-add\ \[aq]src:include:cpp,py,md\[aq]\ \-\-type\-add\ \[aq]src:*.foo\[aq]`
+\f[]
+.fi
+.PP
+Note that type names must consist only of Unicode letters or numbers.
+Punctuation characters are not allowed.
 .RE
 .TP
 .B \-\-type\-clear \f[I]TYPE\f[] ...
diff --git a/doc/rg.1.md b/doc/rg.1.md
index 0bd08504..b920c0ef 100644
--- a/doc/rg.1.md
+++ b/doc/rg.1.md
@@ -267,7 +267,25 @@ Project home page: https://github.com/BurntSushi/ripgrep
   this must be passed to every invocation of rg. Type settings are NOT
   persisted.
 
-      Example: `rg --type-add 'foo:*.foo' -tfoo PATTERN`
+          Example: `rg --type-add 'foo:*.foo' -tfoo PATTERN`
+
+      --type-add can also be used to include rules from other types
+      with the special include directive. The include directive
+      permits specifying one or more other type names (separated by a
+      comma) that have been defined and its rules will automatically
+      be imported into the type specified. For example, to create a
+      type called src that matches C++, Python and Markdown files, one
+      can use:
+
+          `--type-add 'src:include:cpp,py,md'`
+
+      Additional glob rules can still be added to the src type by
+      using the --type-add flag again:
+
+          `--type-add 'src:include:cpp,py,md' --type-add 'src:*.foo'`
+
+      Note that type names must consist only of Unicode letters or
+      numbers. Punctuation characters are not allowed.
 
 --type-clear *TYPE* ...
 : Clear the file type globs previously defined for TYPE. This only clears
diff --git a/ignore/src/types.rs b/ignore/src/types.rs
index 1f032584..213f1dfd 100644
--- a/ignore/src/types.rs
+++ b/ignore/src/types.rs
@@ -66,6 +66,22 @@ assert!(matcher.matched("x.foo", false).is_whitelist());
 // This is ignored because we only selected the `foo` file type.
 assert!(matcher.matched("x.bar", false).is_ignore());
 ```
+
+We can also add file type definitions based on other definitions.
+
+```
+use ignore::types::TypesBuilder;
+
+let mut builder = TypesBuilder::new();
+builder.add_defaults();
+builder.add("foo", "*.foo");
+builder.add_def("bar:include:foo,cpp");
+builder.select("bar");
+let matcher = builder.build().unwrap();
+
+assert!(matcher.matched("x.foo", false).is_whitelist());
+assert!(matcher.matched("y.cpp", false).is_whitelist());
+```
 */
 
 use std::cell::RefCell;
@@ -74,6 +90,7 @@ use std::path::Path;
 use std::sync::Arc;
 
 use globset::{GlobBuilder, GlobSet, GlobSetBuilder};
+use regex::Regex;
 use thread_local::ThreadLocal;
 
 use pathutil::file_name;
@@ -219,7 +236,7 @@ impl<'a> Glob<'a> {
 /// File type definitions can be retrieved in aggregate from a file type
 /// matcher. File type definitions are also reported when its responsible
 /// for a match.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Eq, PartialEq)]
 pub struct FileTypeDef {
     name: String,
     globs: Vec<String>,
@@ -492,10 +509,13 @@ impl TypesBuilder {
     /// Add a new file type definition. `name` can be arbitrary and `pat`
     /// should be a glob recognizing file paths belonging to the `name` type.
     ///
-    /// If `name` is `all` or otherwise contains a `:`, then an error is
-    /// returned.
+    /// If `name` is `all` or otherwise contains any character that is not a
+    /// Unicode letter or number, then an error is returned.
     pub fn add(&mut self, name: &str, glob: &str) -> Result<(), Error> {
-        if name == "all" || name.contains(':') {
+        lazy_static! {
+            static ref RE: Regex = Regex::new(r"^[\pL\pN]+$").unwrap();
+        };
+        if name == "all" || !RE.is_match(name) {
             return Err(Error::InvalidDefinition);
         }
         let (key, glob) = (name.to_string(), glob.to_string());
@@ -505,15 +525,48 @@ impl TypesBuilder {
         Ok(())
     }
 
-    /// Add a new file type definition specified in string form. The format
-    /// is `name:glob`. Names may not include a colon.
+    /// Add a new file type definition specified in string form. There are two
+    /// valid formats:
+    /// 1. `{name}:{glob}`.  This defines a 'root' definition that associates the
+    ///     given name with the given glob.
+    /// 2. `{name}:include:{comma-separated list of already defined names}.
+    ///     This defines an 'include' definition that associates the given name
+    ///     with the definitions of the given existing types.
+    /// Names may not include any characters that are not
+    /// Unicode letters or numbers.
     pub fn add_def(&mut self, def: &str) -> Result<(), Error> {
-        let name: String = def.chars().take_while(|&c| c != ':').collect();
-        let pat: String = def.chars().skip(name.chars().count() + 1).collect();
-        if name.is_empty() || pat.is_empty() {
-            return Err(Error::InvalidDefinition);
+        let parts: Vec<&str> = def.split(':').collect();
+        match parts.len() {
+            2 => {
+                let name = parts[0];
+                let glob = parts[1];
+                if name.is_empty() || glob.is_empty() {
+                    return Err(Error::InvalidDefinition);
+                }
+                self.add(name, glob)
+            }
+            3 => {
+                let name = parts[0];
+                let types_string = parts[2];
+                if name.is_empty() || parts[1] != "include" || types_string.is_empty() {
+                    return Err(Error::InvalidDefinition);
+                }
+                let types = types_string.split(',');
+                // Check ahead of time to ensure that all types specified are
+                // present and fail fast if not.
+                if types.clone().any(|t| !self.types.contains_key(t)) {
+                    return Err(Error::InvalidDefinition);
+                }
+                for type_name in types {
+                    let globs = self.types.get(type_name).unwrap().globs.clone();
+                    for glob in globs {
+                        try!(self.add(name, &glob));
+                    }
+                }
+                Ok(())
+            }
+            _ => Err(Error::InvalidDefinition)
         }
-        self.add(&name, &pat)
     }
 
     /// Add a set of default file type definitions.
@@ -569,6 +622,7 @@ mod tests {
             "rust:*.rs",
             "js:*.js",
             "foo:*.{rs,foo}",
+            "combo:include:html,rust"
         ]
     }
 
@@ -579,10 +633,35 @@ mod tests {
     matched!(match5, types(), vec![], vec![], "index.html");
     matched!(match6, types(), vec![], vec!["rust"], "index.html");
     matched!(match7, types(), vec!["foo"], vec!["rust"], "main.foo");
+    matched!(match8, types(), vec!["combo"], vec![], "index.html");
+    matched!(match9, types(), vec!["combo"], vec![], "lib.rs");
 
     matched!(not, matchnot1, types(), vec!["rust"], vec![], "index.html");
     matched!(not, matchnot2, types(), vec![], vec!["rust"], "main.rs");
     matched!(not, matchnot3, types(), vec!["foo"], vec!["rust"], "main.rs");
     matched!(not, matchnot4, types(), vec!["rust"], vec!["foo"], "main.rs");
     matched!(not, matchnot5, types(), vec!["rust"], vec!["foo"], "main.foo");
+    matched!(not, matchnot6, types(), vec!["combo"], vec![], "leftpad.js");
+
+    #[test]
+    fn test_invalid_defs() {
+        let mut btypes = TypesBuilder::new();
+        for tydef in types() {
+            btypes.add_def(tydef).unwrap();
+        }
+        // Preserve the original definitions for later comparison.
+        let original_defs = btypes.definitions();
+        let bad_defs = vec![
+            // Reference to type that does not exist
+            "combo:include:html,python",
+            // Bad format
+            "combo:foobar:html,rust",
+            ""
+        ];
+        for def in bad_defs {
+            assert!(btypes.add_def(def).is_err());
+            // Ensure that nothing changed, even if some of the includes were valid.
+            assert_eq!(btypes.definitions(), original_defs);
+        }
+    }
 }
diff --git a/src/app.rs b/src/app.rs
index d262e5de..ff61c0a3 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -450,11 +450,24 @@ lazy_static! {
               globs defined inside of ripgrep.\n\nNote that this MUST be \
               passed to every invocation of ripgrep. Type settings are NOT \
               persisted.\n\nExample: \
-              rg --type-add 'foo:*.foo' -tfoo PATTERN.");
+              rg --type-add 'foo:*.foo' -tfoo PATTERN.\n\n\
+              --type-add can also be used to include rules from other types \
+              with the special include directive. The include directive \
+              permits specifying one or more other type names (separated by a \
+              comma) that have been defined and its rules will automatically \
+              be imported into the type specified. For example, to create a \
+              type called src that matches C++, Python and Markdown files, one \
+              can use:\n\n\
+              --type-add 'src:include:cpp,py,md'\n\n\
+              Additional glob rules can still be added to the src type by \
+              using the --type-add flag again:\n\n\
+              --type-add 'src:include:cpp,py,md' --type-add 'src:*.foo'\n\n\
+              Note that type names must consist only of Unicode letters or \
+              numbers. Punctuation characters are not allowed.");
         doc!(h, "type-clear",
              "Clear globs for given file type.",
              "Clear the file type globs previously defined for TYPE. This \
-              only clears the default tpye definitions that are found inside \
+              only clears the default type definitions that are found inside \
               of ripgrep.\n\nNote that this MUST be passed to every \
               invocation of ripgrep. Type settings are NOT persisted.");
 
diff --git a/tests/tests.rs b/tests/tests.rs
index 1802e186..fa024060 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -308,6 +308,17 @@ sherlock!(file_type_add, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
     assert_eq!(lines, "file.wat:Sherlock\n");
 });
 
+sherlock!(file_type_add_compose, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
+    wd.create("file.py", "Sherlock");
+    wd.create("file.rs", "Sherlock");
+    wd.create("file.wat", "Sherlock");
+    cmd.arg("--type-add").arg("wat:*.wat");
+    cmd.arg("--type-add").arg("combo:include:wat,py").arg("-t").arg("combo");
+    let lines: String = wd.stdout(&mut cmd);
+    println!("{}", lines);
+    assert_eq!(lines, "file.py:Sherlock\nfile.wat:Sherlock\n");
+});
+
 sherlock!(glob, "Sherlock", ".", |wd: WorkDir, mut cmd: Command| {
     wd.create("file.py", "Sherlock");
     wd.create("file.rs", "Sherlock");