How do people navigate along a crowded sidewalk, reach for and pick up a glass of water, balance a tray of dishes, or type on a keyboard? How do highly skilled athletes, musicians, and dancers move with such efficiency and grace? What goes wrong when our ability to move becomes impaired and how can this ability be restored? Why is it so difficult to build machines to perform the same activities that most of us carry out effortlessly? This course is a graduate level introduction to the topic of perception and action. We will explore this topic from information processing, computational, dynamical systems, and ecological perspectives, review current empirical and computational research, and consider some applications, including training, rehabilitation, human-machine interaction, and robotics.