Cell adhesion molecules (CAMs) play important roles in specifying cell-cell interactions during development, regeneration, and modification of synaptic activity. The close homolog of L1 (CHL1), a recently identified member of the immunoglobulin superfamily of cell adhesion molecules, is localizably expressed in the nervous system. CHL1 interacts with like molecules (homophilic interaction) and non-like molecules (heterophilic interaction) on neighboring cells or the extracellular matrix to regulate axon outgrowth and fasciculation, neuronal migration and survival, synaptic plasticity and regeneration after trauma.