Human performance plays an important role in system performance and is influenced by a wide set of internal, organizational, and environmental factors. Human-robot systems are being developed for a large number of domains, including in-home care, military deployments, emergency response, industrial robots, and therapeutic applications. Human performance modeling provides the opportunity to investigate multiple system prototypes and theories regarding human performance that can be further evaluated in human-inthe-loop experiments, to quickly adapt to rapidly changing robotic technology, and to represent human behavior in extreme conditions. Interacting with robots also influences human performance, and models of the human-robot system provide an avenue to investigate the impact on human performance that the human-robot teaming elicits. This chapter provides an overview of examples representing common methods for assessing human performance in human-robot systems. The topics are summarized in Table 3.2 and include a description of human performance modeling, a summary of commonly used human performance modeling tools, examples of human performance modeling with a focus on its application in human-robot systems, information regarding the validation of models, and guidelines for implementing human performance modeling techniques for robotics.