diff --git a/include/osg/Notify b/include/osg/Notify
index ae0d37e22..dbd7d2233 100644
--- a/include/osg/Notify
+++ b/include/osg/Notify
@@ -44,6 +44,9 @@ extern OSG_EXPORT void setNotifyLevel(NotifySeverity severity);
 /** get the notify level. */
 extern OSG_EXPORT NotifySeverity getNotifyLevel();
 
+/** is notification enabled, given the current setNotifyLevel() setting? */
+extern OSG_EXPORT bool isNotifyEnabled(NotifySeverity severity);
+
 /** initialize notify level. */
 extern OSG_EXPORT bool initNotifyLevel();
 
diff --git a/include/osg/Program b/include/osg/Program
index 0bb9b77b5..c608f388f 100644
--- a/include/osg/Program
+++ b/include/osg/Program
@@ -12,7 +12,7 @@
 */
 
 /* file:        include/osg/Program
- * author:      Mike Weiblen 2005-05-05
+ * author:      Mike Weiblen 2005-07-01
 */
 
 #ifndef OSG_PROGRAM
@@ -132,6 +132,7 @@ class OSG_EXPORT Program : public osg::StateAttribute
 
                 void requestLink();
                 void linkProgram();
+                void validateProgram();
                 bool needsLink() const {return _needsLink;}
                 bool isLinked() const {return _isLinked;}
                 bool getInfoLog( std::string& infoLog ) const;
diff --git a/src/osg/Notify.cpp b/src/osg/Notify.cpp
index f151dbe45..3cd3b3a12 100644
--- a/src/osg/Notify.cpp
+++ b/src/osg/Notify.cpp
@@ -77,6 +77,11 @@ bool osg::initNotifyLevel()
 
 }
 
+bool osg::isNotifyEnabled( osg::NotifySeverity severity )
+{
+    return severity<=g_NotifyLevel;
+}
+
 #if defined(WIN32) && !(defined(__CYGWIN__) || defined(__MINGW32__))
 const char* NullStreamName = "nul";
 #else
diff --git a/src/osg/Program.cpp b/src/osg/Program.cpp
index b8b6804d3..14ad61e34 100644
--- a/src/osg/Program.cpp
+++ b/src/osg/Program.cpp
@@ -13,7 +13,7 @@
 */
 
 /* file:        src/osg/Program.cpp
- * author:      Mike Weiblen 2005-05-05
+ * author:      Mike Weiblen 2005-07-01
 */
 
 #include <fstream>
@@ -2064,6 +2064,12 @@ void Program::apply( osg::State& state ) const
     if( pcp->needsLink() ) compileGLObjects( state );
     if( pcp->isLinked() )
     {
+        // for shader debugging: to minimize performance impact,
+        // optionally validate based on notify level.
+        // TODO: enable this using notify level, or perhaps its own getenv()?
+        if( osg::isNotifyEnabled(osg::INFO) )
+            pcp->validateProgram();
+
         pcp->useProgram();
         state.setLastAppliedProgramObject(pcp);
     }
@@ -2152,6 +2158,7 @@ void Program::PerContextProgram::linkProgram()
     osg::notify(osg::INFO)
         << "Linking osg::Program \"" << _program->getName() << "\""
         << " id=" << _glProgramHandle
+        << " contextID=" << _contextID
         <<  std::endl;
 
     _uniformInfoMap.clear();
@@ -2258,6 +2265,27 @@ void Program::PerContextProgram::linkProgram()
     osg::notify(osg::INFO) << std::endl;
 }
 
+void Program::PerContextProgram::validateProgram()
+{
+    GLint validated = GL_FALSE;
+    _extensions->glValidateProgram( _glProgramHandle );
+    _extensions->glGetProgramiv( _glProgramHandle, GL_VALIDATE_STATUS, &validated );
+    if( validated == GL_TRUE)
+        return;
+
+    osg::notify(osg::INFO)
+        << "glValidateProgram FAILED \"" << _program->getName() << "\""
+        << " id=" << _glProgramHandle
+        << " contextID=" << _contextID
+        <<  std::endl;
+
+    std::string infoLog;
+    if( getInfoLog(infoLog) )
+        osg::notify(osg::INFO) << "infolog:\n" << infoLog << std::endl;
+
+    osg::notify(osg::INFO) << std::endl;
+}
+
 bool Program::PerContextProgram::getInfoLog( std::string& infoLog ) const
 {
     return _extensions->getProgramInfoLog( _glProgramHandle, infoLog );