Audit studies have gained popularity in the social sciences, producing important insights about discrimination and bias across a range of social statuses, such as race and gender. Yet, important questions persist about why, when, and where discrimination and bias emerge. In this chapter, I suggest that tackling these issues is a central task of audit studies and discuss emerging frontiers of audit study research that are attempting to address these pressing issues. First, audit studies can contribute to our understanding of why discrimination occurs by incorporating strategies to uncover the mechanisms that drive the empirical patterns observed in the data. Second, audit studies can provide insights about when and where discrimination and bias occur by paying attention to theoretically important variation in average treatment effects and clarifying the representativeness of a given set of findings. Throughout, I present evidence from recent audit study research that pushes the boundaries on each of these frontiers and discuss potential paths forward to continue to advance the design, implementation, and contribution of this method to social science research.