The development of proper motor functions is critical to the survival of most animals, but how are stereotypical movement patterns, such as walking and breathing, first generated and then refined? On p. 3707, Sarah Crisp and colleagues report that the first muscle contractions seen in Drosophila embryos are generated by spontaneous activity in the muscle cells themselves. However, a drastic change in the pattern of muscle contraction later takes place, with simultaneous bursts of activity occurring in numerous muscles on both sides of the embryo. This transition, the authors find, requires motor, but not sensory, activity, which consists not of the spontaneous firing of individual motoneurons, but rather of the activity of a developing central, pattern-generating motor network. Following the onset of this activity, the muscle contraction pattern that occurs during these bursts begins increasingly to resemble that of crawling larvae. As such, the authors propose that these activity bursts are important for the maturation and development of the central motor network and for coordinated movement.