Hypothesized relationships between asymmetric brain processes and movement-related asymmetries are reviewed. Theories that attribute asymmetric preference and performance to hemisphere dominance have been superseded by more complex ideas: motor-specific and more global hemispheric specializations are considered to influence movement organization. Environmentally conditioned preferences and their relationship to preferential asymmetric movements are also addressed. The literature suggests that laterality may be dynamic, because task requirements have been shown to override asymmetric brain influences. This observation of the nature of laterality may result in a more flexible approach to the reeducation of preference and performance in brain-injured patients.