The E3 ubiquitin ligases Cdc20-anaphase-promoting complex (Cdc20-APC) and Cdh1-APC play key roles in cell cycle transitions in proliferating cells. Remarkably, these ubiquitin ligases are also expressed in postmitotic neurons, raising interest in non-mitotic functions of the APC. Cdh1-APC has been implicated in diverse functions in the nervous system, from the control of axon growth and patterning to synapse development to neuron survival. However, until recently the question of whether Cdc20-APC harbors functions in neurons remained unanswered. New evidence from Kim et al. (2009) has uncovered a novel role for Cdc20-APC in dendrite growth and elaboration in post-mitotic neurons. Interestingly, the histone deacetylase HDAC6 augments Cdc20-APC activity at the centrosome by promoting Cdc20 polyubiquitination. In turn, Cdc20-APC triggers the degradation of the centrosomally localized protein Id1 and thereby promotes dendrite growth and elaboration. These findings have advanced our understanding of APC biology in neuronal connectivity in the brain.