Abstract: Early in development the nervous system is constructed with far too many neurons that make an excessive number of synaptic connections. Later, a wave of neuronal remodeling radically reshapes nervous system wiring and cell numbers through the selective elimination of excess synapses, axons and dendrites, and even whole neurons. This remodeling is widespread across the nervous system, extensive in terms of how much individual brain regions can change (e.g. in some cases >50% of neurons integrated into vertebrate brain circuits are eliminated) and thought to be essential for optimizing nervous system function. Perturbations of neuronal remodeling are believed to underlie devastating neurodevelopmental disorders including autism spectrum disorder, schizophrenia, and epilepsy. This talk will discuss our efforts to use the relatively simple nervous system of Drosophila to understand the mechanistic basis by which cells, or parts of cells, are specified for removal and eliminated from the nervous system.