The way complex movements are coordinated has been the object of research for nearly a century. Although much progress has been made, this is still a very active field of research. Moreover, there is a current debate between two psychological theories both aiming to explain how our movements are coordinated. The older computational theory proposes that the brain is organised on the model of a computer and sends programmes to activate muscles. The emergent ecological-dynamic theory argues that it is through evolution that self-organised systems emerge. New progress in these two theories will be presented and contrasted in view of development, learning, and motor control issues.