Neuronal morphogenesis is driven by cytoskeletal changes in which microtubules play a leading role. A very heterogeneous group of microtubule-associated proteins (MAPs) seems to control the dynamics and contribute to the organization of the microtubule cytoskeleton. Of great importance in this regard is the developmental regulation of the expression of certain MAPs in specific neuronal compartments. Furthermore, MAP functionality is also modulated by phosphorylation and dephosphorylation events. A correlation between the expression and/or phosphorylation of distinct MAPs and definite stages of neuronal development may be established. A putative role in synaptic plasticity for MAP modifications similar to those occurring during development can be anticipated. Interestingly, gross alterations in microtubule-associated proteins are found in several neuropathologies including Alzheimer's disease. In this review we focus on recent advances in the understanding of the molecular properties of major neuronal MAPs which may be relevant to these issues.