In this tutorial, we will start out by discussing some unique challenges that optoelectronics faces, and then talk about some of the more common causes of device failure. We will briefly discuss the root causes for the failure, before going into popular techniques for diagnosing root cause. A number of suggestions for improving the speed and accuracy of diagnosis will be given at the conclusion. The tutorial will focus primarily on semiconductor laser failure, since the other failure mechanisms have root causes similar to those of other electronics.