The diverse functions of the nervous system depend on the establishment of precise connections between different groups of neurons, and in the case of the motor system, skeletal muscles. Our studies investigate the development of the spinal motor circuits that enable limb movements and respiratory functions, focusing on the relationships between neuronal identity, axon growth and pathfinding, and selection of synaptic targets. By investigating the molecular details of how these processes, we can gain crucial insights into the mechanisms and logic behind the construction of neural networks. This knowledge will help us determine the underlying causes of both neurodevelopment defects and neurological diseases, and means for devising new therapeutic strategies to repair or regenerate diseased or damaged neural tissues.