diff --git a/bn-tests.rkt b/bn-tests.rkt
index 8dec81e..6012f95 100644
--- a/bn-tests.rkt
+++ b/bn-tests.rkt
@@ -35,4 +35,8 @@
       (test-case "Constructing networks from forms"
         (let ([s (make-state '((x . #t) (y . #f)))]
               [f (update-func-form->update-func '(and x y))])
-          (check-equal? (f s) #f))))))
+          (check-equal? (f s) #f))
+        (let ([bn (bn-form->bn (make-hash '((a . (and a b)) (b . (not b)))))]
+              [s (make-state '((a . #t) (b . #t)))])
+          (check-equal? ((hash-ref bn 'a) s)
+                        #t))))))
diff --git a/bn.rkt b/bn.rkt
index 9d3fe20..0aff9fa 100644
--- a/bn.rkt
+++ b/bn.rkt
@@ -10,7 +10,8 @@
 (require "utils.rkt")
 
 (provide Variable State UpdateFunc Network
-         update make-state make-bn update-func-form->update-func)
+         update make-state make-bn update-func-form->update-func
+         bn-form->bn)
 
 
 ;;; =================
@@ -72,3 +73,10 @@
 (define (update-func-form->update-func form)
   (lambda ([s : State])
     (cast (eval-with1 (cast s (HashTable Variable Any)) form) Boolean)))
+
+;;; Build a Network from a Network form.
+(: bn-form->bn (-> NetworkForm Network))
+(define (bn-form->bn bnf)
+  (make-hash
+   (hash-map bnf (lambda ([x : Variable] [form : UpdateFuncForm])
+                   (cons x (update-func-form->update-func form))))))