diff --git a/abnf.cabal b/abnf.cabal
--- a/abnf.cabal
+++ b/abnf.cabal
@@ -2,7 +2,7 @@
 -- see http://haskell.org/cabal/users-guide/
 
 name:                abnf
-version:             0.3.0.0
+version:             0.3.1.0
 synopsis:            Parse ABNF and generate parsers for the specified document
 description:         You can use this library to parse an ABNF document and
                      generate a parser from that ABNF to read a document
diff --git a/src/Text/ABNF/Document.hs b/src/Text/ABNF/Document.hs
--- a/src/Text/ABNF/Document.hs
+++ b/src/Text/ABNF/Document.hs
@@ -27,6 +27,7 @@
     , squashDocument
     , squashDocumentOn
     , squashContent
+    , lookupDocument
     -- * Parsing documents
     -- | Re-exported from "Text.ABNF.Document.Parser"
     , generateParser
@@ -41,6 +42,7 @@
                                      , squashDocument
                                      , squashDocumentOn
                                      , squashContent
+                                     , lookupDocument
                                      )
 
 import Text.ABNF.Document.Parser ( generateParser
diff --git a/src/Text/ABNF/Document/Operations.hs b/src/Text/ABNF/Document/Operations.hs
--- a/src/Text/ABNF/Document/Operations.hs
+++ b/src/Text/ABNF/Document/Operations.hs
@@ -11,8 +11,10 @@
 
 module Text.ABNF.Document.Operations where
 
+import Control.Monad (join)
 import Data.Maybe (catMaybes)
 import Data.Monoid ((<>))
+import qualified Data.Text as Text
 
 import Text.ABNF.Document.Types
 
@@ -51,3 +53,16 @@
 squashContent [] = mempty
 squashContent ((Terminal a):xs) = a <> squashContent xs
 squashContent ((NonTerminal (Document _ conts)):xs) = squashContent conts <> squashContent xs
+
+-- | Looks up nested 'Document's with a particular identifier.
+-- NB: Will not recurse into matching documents.
+lookupDocument :: forall a. Text.Text -- ^ Identifier to search for
+               -> Document a          -- ^ 'Document' to search in
+               -> [Document a]
+lookupDocument ident doc@(Document ident2 conts) | ident2 == ident = [doc]
+                                                 | otherwise = join $ lookupNT <$> conts
+    where
+        lookupNT :: Content a -> [Document a]
+        lookupNT (Terminal _) = []
+        lookupNT (NonTerminal d) = lookupDocument ident d
+