diff --git a/gtsam/base/Makefile.am b/gtsam/base/Makefile.am
index 1acc61b7d..ba13e1641 100644
--- a/gtsam/base/Makefile.am
+++ b/gtsam/base/Makefile.am
@@ -24,7 +24,7 @@ endif
 
 # Testing
 headers += Testable.h TestableAssertions.h numericalDerivative.h
-sources += timing.cpp 
+sources += timing.cpp debug.cpp
 
 # Lie Groups
 headers += Lie.h Lie-inl.h lieProxies.h LieScalar.h
diff --git a/gtsam/base/debug.cpp b/gtsam/base/debug.cpp
new file mode 100644
index 000000000..57951d756
--- /dev/null
+++ b/gtsam/base/debug.cpp
@@ -0,0 +1,16 @@
+/**
+ * @file    debug.cpp
+ * @brief   
+ * @author  Richard Roberts
+ * @created Feb 1, 2011
+ */
+
+#include <gtsam/base/debug.h>
+
+namespace gtsam {
+
+#ifdef GTSAM_ENABLE_DEBUG
+  FastMap<std::string, ValueWithDefault<bool,false> > debugFlags;
+#endif
+
+}
diff --git a/gtsam/base/debug.h b/gtsam/base/debug.h
new file mode 100644
index 000000000..215766661
--- /dev/null
+++ b/gtsam/base/debug.h
@@ -0,0 +1,50 @@
+/**
+ * @file    debug.h
+ * @brief   Global debugging flags
+ * @author  Richard Roberts
+ * @created Feb 1, 2011
+ */
+
+#pragma once
+
+#include <gtsam/base/FastMap.h>
+#include <gtsam/base/types.h>
+#include <string>
+
+
+// This file defines granular debugging flags that may be switched on and off
+// at run time.  Typical usage is 'if(ISDEBUG("myFunction"))' to check if the
+// 'myFunction' flag is enabled, and SETDEBUG("myFunction", true) to enable
+// this flag, or SETDEBUG("myFunction", false) to disable it.
+//
+// Debug flags are created automatically as they are accessed, so they can be
+// used immediately without explicitly creating them.  Each flag defaults to
+// 'false', i.e. disabled.
+//
+// For these macro to have any effect, granular debugging must be enabled by
+// defining GTSAM_ENABLE_DEBUG.  If NDEBUG is not defined, then
+// GTSAM_ENABLE_DEBUG will be automatically defined and thus granular
+// debugging enabled.
+
+#ifndef NDEBUG
+#ifndef GTSAM_ENABLE_DEBUG
+#define GTSAM_ENABLE_DEBUG
+#endif
+#endif
+
+#ifdef GTSAM_ENABLE_DEBUG
+
+namespace gtsam {
+  extern FastMap<std::string, ValueWithDefault<bool,false> > debugFlags;
+}
+
+#define ISDEBUG(S) (gtsam::debugFlags[S])
+#define SETDEBUG(S,V) (gtsam::debugFlags[S] = (V))
+
+#else
+
+#define ISDEBUG(S) (false)
+#define SETDEBUG(S,V) (false)
+
+#endif
+