The Exocyst complex is an evolutionarily-conserved, well-studied mediator of polarized cell growth in budding yeast, but its function(s) in multicellular organisms are not well understood. Using Drosophila dendritic arborization neurons as model cells, we find that the Exocyst is required for axon and dendrite regeneration after injury and dendrite regrowth after developmental pruning in vivo. We are also investigating how the smooth endoplasmic reticulum (SER) might induce exocytosis at the growing tip via Ca2+ release.