This is the 33rd volume in the Minnesota Symposium on Child Psychology held in October 2002. The symposium was held to honor the scientific and mentoring contributions of Anne Danielson Pick and Herbert L. Pick, Jr.--two longtime and beloved professors of the Institute of Child Development. It focused on "Action as an Organizer of Learning and Development" and integrated the best and most innovative research on the role of action in perceiving and understanding. Taken together, the book captures the intellectual excitement that characterized the 33rd symposium and appeals to developmental psychologists, particularly those interested in perceptual development.