diff --git a/src/lib.rs b/src/lib.rs
index a7f7370..b98c8df 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,4 +5,8 @@ extern crate bit_set;
 
 pub use puzzle::Puzzle;
 
+/// A puzzle variable token.
+#[derive(Copy,Clone,Debug,Eq,PartialEq)]
+pub struct VarToken(usize);
+
 mod puzzle;
diff --git a/src/puzzle.rs b/src/puzzle.rs
index 0d0881a..ab761d2 100644
--- a/src/puzzle.rs
+++ b/src/puzzle.rs
@@ -1,7 +1,8 @@
 //! The puzzle's state and rules.
 
+use ::VarToken;
+
 /// The puzzle to be solved.
-#[allow(dead_code)]
 pub struct Puzzle {
     // The number of variables in the puzzle.
     num_vars: usize,
@@ -20,4 +21,19 @@ impl Puzzle {
             num_vars: 0,
         }
     }
+
+    /// Allocate a new puzzle variable, without inserting any
+    /// candidates.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut puzzle = puzzle_solver::Puzzle::new();
+    /// puzzle.new_var();
+    /// ```
+    pub fn new_var(&mut self) -> VarToken {
+        let var = VarToken(self.num_vars);
+        self.num_vars = self.num_vars + 1;
+        var
+    }
 }