diff --git a/vtkm/Assert.h b/vtkm/Assert.h
new file mode 100644
index 000000000..15af5e243
--- /dev/null
+++ b/vtkm/Assert.h
@@ -0,0 +1,45 @@
+//============================================================================
+//  Copyright (c) Kitware, Inc.
+//  All rights reserved.
+//  See LICENSE.txt for details.
+//  This software is distributed WITHOUT ANY WARRANTY; without even
+//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+//  PURPOSE.  See the above copyright notice for more information.
+//
+//  Copyright 2016 Sandia Corporation.
+//  Copyright 2016 UT-Battelle, LLC.
+//  Copyright 2016 Los Alamos National Security.
+//
+//  Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
+//  the U.S. Government retains certain rights in this software.
+//
+//  Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
+//  Laboratory (LANL), the U.S. Government retains certain rights in
+//  this software.
+//============================================================================
+
+#ifndef vtk_m_Assert_h
+#define vtk_m_Assert_h
+
+#include <assert.h>
+
+/// \def VTKM_ASSERT(condition)
+///
+/// Asserts that \a condition resolves to true.  If \a condition is false,
+/// then a diagnostic message is outputted and execution is terminated. The
+/// behavior is essentially the same as the POSIX assert macro, but is
+/// wrapped for added portability.
+///
+/// Like the POSIX assert macro, the check will be removed when compiling
+/// in non-debug mode (specifically when NDEBUG is defined), so be prepared
+/// for the possibility that the condition is never evaluated.
+///
+#if !defined(NDEBUG)
+#define VTKM_ASSERT(condition) \
+  assert(condition)
+#else
+#define VTKM_ASSERT(condition)
+#endif
+
+
+#endif //vtk_m_Assert_h
diff --git a/vtkm/CMakeLists.txt b/vtkm/CMakeLists.txt
index a5ccea274..802caed90 100644
--- a/vtkm/CMakeLists.txt
+++ b/vtkm/CMakeLists.txt
@@ -21,6 +21,7 @@
 include_directories(${Boost_INCLUDE_DIRS})
 
 set(headers
+  Assert.h
   BinaryPredicates.h
   BinaryOperators.h
   CellShape.h
diff --git a/vtkm/Matrix.h b/vtkm/Matrix.h
index 12ebcd19c..2a842cb04 100644
--- a/vtkm/Matrix.h
+++ b/vtkm/Matrix.h
@@ -22,6 +22,7 @@
 #ifndef vtk_m_Matrix_h
 #define vtk_m_Matrix_h
 
+#include <vtkm/Assert.h>
 #include <vtkm/Math.h>
 #include <vtkm/Types.h>
 #include <vtkm/TypeTraits.h>
@@ -59,6 +60,8 @@ public:
   VTKM_EXEC_CONT_EXPORT
   const vtkm::Vec<ComponentType, NUM_COLUMNS> &
   operator[](vtkm::IdComponent rowIndex) const {
+    VTKM_ASSERT(rowIndex >= 0);
+    VTKM_ASSERT(rowIndex < this->NUM_ROWS);
     return this->Components[rowIndex];
   }
 
@@ -68,6 +71,8 @@ public:
   VTKM_EXEC_CONT_EXPORT
   vtkm::Vec<ComponentType, NUM_COLUMNS> &
   operator[](vtkm::IdComponent rowIndex) {
+    VTKM_ASSERT(rowIndex >= 0);
+    VTKM_ASSERT(rowIndex < this->NUM_ROWS);
     return this->Components[rowIndex];
   }
 
@@ -77,6 +82,10 @@ public:
   VTKM_EXEC_CONT_EXPORT
   const ComponentType &
   operator()(vtkm::IdComponent rowIndex, vtkm::IdComponent colIndex) const {
+    VTKM_ASSERT(rowIndex >= 0);
+    VTKM_ASSERT(rowIndex < this->NUM_ROWS);
+    VTKM_ASSERT(colIndex >= 0);
+    VTKM_ASSERT(colIndex < this->NUM_COLUMNS);
     return (*this)[rowIndex][colIndex];
   }
 
@@ -86,6 +95,10 @@ public:
   VTKM_EXEC_CONT_EXPORT
   ComponentType &
   operator()(vtkm::IdComponent rowIndex, vtkm::IdComponent colIndex) {
+    VTKM_ASSERT(rowIndex >= 0);
+    VTKM_ASSERT(rowIndex < this->NUM_ROWS);
+    VTKM_ASSERT(colIndex >= 0);
+    VTKM_ASSERT(colIndex < this->NUM_COLUMNS);
     return (*this)[rowIndex][colIndex];
   }
 
diff --git a/vtkm/Types.h b/vtkm/Types.h
index 95b2f35f5..a7d0f1095 100644
--- a/vtkm/Types.h
+++ b/vtkm/Types.h
@@ -24,6 +24,8 @@
 #include <vtkm/internal/Configure.h>
 #include <vtkm/internal/ExportMacros.h>
 
+#include <vtkm/Assert.h>
+
 VTKM_THIRDPARTY_PRE_INCLUDE
 #include <boost/mpl/or.hpp>
 #include <boost/type_traits/is_floating_point.hpp>
@@ -806,11 +808,15 @@ public:
   VTKM_EXEC_CONT_EXPORT
   const ComponentType &operator[](vtkm::IdComponent idx) const
   {
+    VTKM_ASSERT(idx >= 0);
+    VTKM_ASSERT(idx < this->NUM_COMPONENTS);
     return this->Components[idx];
   }
   VTKM_EXEC_CONT_EXPORT
   ComponentType &operator[](vtkm::IdComponent idx)
   {
+    VTKM_ASSERT(idx >= 0);
+    VTKM_ASSERT(idx < this->NUM_COMPONENTS);
     return this->Components[idx];
   }
 
diff --git a/vtkm/VecVariable.h b/vtkm/VecVariable.h
index 0d8e36933..64b01739b 100644
--- a/vtkm/VecVariable.h
+++ b/vtkm/VecVariable.h
@@ -20,6 +20,7 @@
 #ifndef vtk_m_VecVariable_h
 #define vtk_m_VecVariable_h
 
+#include <vtkm/Assert.h>
 #include <vtkm/Math.h>
 #include <vtkm/Types.h>
 #include <vtkm/TypeTraits.h>
@@ -48,6 +49,7 @@ public:
   VecVariable(const vtkm::VecVariable<ComponentType,SrcSize> &src)
     : NumComponents(src.GetNumberOfComponents())
   {
+    VTKM_ASSERT(this->NumComponents <= MaxSize);
     for (vtkm::IdComponent index = 0; index < this->NumComponents; index++)
     {
       this->Data[index] = src[index];
@@ -59,6 +61,7 @@ public:
   VecVariable(const vtkm::Vec<ComponentType,SrcSize> &src)
     : NumComponents(SrcSize)
   {
+    VTKM_ASSERT(this->NumComponents <= MaxSize);
     for (vtkm::IdComponent index = 0; index < this->NumComponents; index++)
     {
       this->Data[index] = src[index];
@@ -96,6 +99,7 @@ public:
   VTKM_EXEC_CONT_EXPORT
   void Append(ComponentType value)
   {
+    VTKM_ASSERT(this->NumComponents < MaxSize);
     this->Data[this->NumComponents] = value;
     this->NumComponents++;
   }