Given what evidence there is for the molecular and functional nature of cytokines and their cognate binding proteins in the immune system and the emerging similarities or even identities for these ligands and receptors in the nervous system, two general models may be relevant. The first emerging pattern is that receptors for related but distinct trophic factors in the CNS are in many instances multichain complexes with one or more shared components. The shared components of the receptor complex may be either signal- or nonsignal-transducing chains. A second emerging motif is that related ligands and related receptors fall into gene families. Undoubtedly, these models will facilitate the cloning of novel members of these families whose function is quite specific to the nervous system and in particular to glial cells. This article will review the function of the receptors for cytokines and families of differentiation/survival/growth factors as they operate on astrocytes, microglia, and oligodendrocytes in development, health, and disease.