Machine-learning algorithms, especially classifiers, are becoming prevalent in safety and security-critical applications. The susceptibility of some types of classifiers to being evaded by adversarial input data has been explored in domains such as spam filtering, but with the rapid growth in adoption of machine learning in multiple application domains amplifies the extent and severity of this vulnerability landscape. We propose to (1) develop predictive metrics that characterize the degree to which a neural-network-based image classifier used in domains such as face recognition (say, for surveillance and authentication) can be evaded through attacks that are both practically realizable and inconspicuous, and (2) develop methods that make these classifiers, and the applications that incorporate them, robust to such interference. We will examine how to manipulate images to fool classifiers in various ways, and how to do so in a way that escapes the suspicion of even human onlookers. Armed with this understanding of the weaknesses of popular classifiers and their modes of use, we will develop explanations of model behavior to help identify the presence of a likely attack; and generalize these explanations to harden models against future attacks.