diff --git a/rs-tests.rkt b/rs-tests.rkt
index f827539..f2fdb93 100644
--- a/rs-tests.rkt
+++ b/rs-tests.rkt
@@ -32,7 +32,8 @@
          [rs (make-immutable-hash (list (cons 'a r1) (cons 'b r2)))]
          [dyn (dynamics rs)]
          [state1 (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))]
-         [sgr (dds-build-state-graph-annotated dyn (set state1))])
+         [sgr (dds-build-state-graph-annotated dyn (set state1))]
+         [ip (build-interactive-process rs (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))])
     (check-equal? (dds-step-one-annotated dyn state1)
                   (set (cons
                         (set 'a 'b)
@@ -70,4 +71,6 @@
     (check-equal? (edge-weight sgr
                                (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))
                                (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z))))
-                  (set (set 'a 'b)))))
+                  (set (set 'a 'b)))
+
+    (check-equal? sgr ip)))
diff --git a/rs.rkt b/rs.rkt
index 3bd66e3..ac04a48 100644
--- a/rs.rkt
+++ b/rs.rkt
@@ -25,7 +25,8 @@
                [dds-build-state-graph (-> dynamics? (set/c state? #:kind 'dont-care) graph?)]
                [dds-build-n-step-state-graph (-> dynamics? (set/c state? #:kind 'dont-care) number? graph?)]
                [dds-build-state-graph-annotated (-> dynamics? (set/c state? #:kind 'dont-care) graph?)]
-               [dds-build-n-step-state-graph-annotated (-> dynamics? (set/c state? #:kind 'dont-care) number? graph?)])
+               [dds-build-n-step-state-graph-annotated (-> dynamics? (set/c state? #:kind 'dont-care) number? graph?)]
+               [build-interactive-process (-> reaction-system/c (listof (set/c species?)) graph?)])
  ;; Predicates
  (contract-out [species? (-> any/c boolean?)])
  ;; Contracts
@@ -162,3 +163,11 @@
           (apply-rs-annotate (set-union res ctx) rest-ctx)]
          [(state res '())
           (apply-rs-annotate res '())])))])
+
+;;; Builds the state graph of a reaction system driven by a given
+;;; context sequence.  When the context sequence is exhausted, keeps
+;;; running the system without contexts.  In other words, the context
+;;; sequence is padded with empty contexts at the end.
+(define (build-interactive-process rs contexts)
+  (dds-build-state-graph-annotated (dynamics rs)
+                                   (set (state (set) contexts))))