Determining when a machine learning model is “good enough” is challenging since held-out accuracy metrics significantly overestimate real-world performance. In this talk, I will describe automated techniques to detect bugs that can occur naturally when a model is deployed. I will start by approaches to identify “semantically equivalent” adversaries that should not change the meaning of the input, but lead to a change in the model’s predictions. Then I will present our work on evaluating the consistency behavior of the model by exploring performance on new instances that are “implied” by the model’s predictions. I will also describe a method to understand and debug models by adversarially modifying the training data to change the model’s predictions. The talk will include applications of these ideas on a number of NLP tasks, such as reading comprehension, visual QA, and knowledge graph completion.