Pericytes are mural cells that enwrap capillaries and are critically important in maintaining the health and homeostasis of the microcirculation. Although pericytes are most well-known for their role in providing stabilizing and supporting signals to the capillary endothelium, they also play a part in regulating immune cell recruitment, blood flow, and capillary permeability. Additionally, pericytes help modulate angiogenesis, and they have been shown to possess stem cell characteristics and pluripotency capabilities. Hence, the study of pericyte dynamics—how pericytes contribute to the growth and adaptation of the microvasculature, the signals that drive their phenotypic differentiation and the consequences thereof, and the alterations in microvascular function that ensue—has become a recent focus of research. An emerging body of literature suggests that pericyte dynamics in various tissues and organs throughout the body may be altered by diseases such as diabetes, Alzheimer’s disease (AD), and fibrotic disease. Furthermore, alterations in pericyte dynamics likely contribute to the pathogenesis and progression of these and other diseases. This chapter summarizes the known functions of pericytes and how they adapt to disease, their origins and plasticity, and their potential to serve as therapeutic targets in different diseases. Throughout this chapter, we emphasize the experimental model systems that have been used to study pericytes as well as the challenges associated with identifying and isolating them. We conclude this chapter by highlighting some of the unanswered questions about pericyte identity, function, and dynamics.