Generation of force is critical for many cellular processes. Central to these processes are motor proteins, proteins that use the cell’s chemical energy to create directed motion. Myosins are a family of motor proteins that generate motion along the filamentous protein actin using the energy of ATP hydrolysis. Single-molecule studies of myosin motors have led to a detailed understanding of their force-generating mechanism. However, an understanding of how a myosin functions also requires an understanding of how the motor is regulated by its cellular environment. In this talk, I will discuss single molecule optical trap studies as well as studies conducted in a cellular system that have helped us understand how a particular myosin class, myosin VI, is regulated in the cell. I will also describe preliminary results for studies of the regulated activities of two other myosin classes.