Virtual humans (VHs) are digital anthropomorphic characters that exist within virtual worlds but are designed to perceive, understand and interact with real-world humans. Although typically conceived as practical tools to assist in a range of application (e.g., HCI, training and entertainment), the technology is gaining interest as a methodological tool for studying human cognition. VHs not only simulate the cognitive abilities of people, but also many of the embodied and social aspects of human behavior more traditionally studied in fields outside of cognitive science. By integrating multiple cognitive capabilities (e.g., language, gesture, emotion, and the control problems associated with navigating and interacting with a simulated virtual world) and requiring these processes to support real-time interactions with people, VHs create a unique and challenging environment within which to develop and validate cognitive theories. In this tutorial, we will review recent advances in VH technologies, demonstrate examples of use of VHs in cognitive science research and provide hands on training using our Virtual Human Toolkit (http://vhtoolkit.ict.usc.edu/).