Presynaptic nerve terminals rely heavily on membrane traffic to maintain efficient neurotransmission between cells. It is often assumed that, as neurons can fire action potentials at high frequency, the cell biological machinery for vesicle cycling must be highly specialized. Here, we examine the demands that are placed on the recycling machinery in three model systems used to characterize vertebrate vesicle recycling--small hippocampal synapses, calyx-type brainstem synapses, and ribbon-type sensory synapses--and the molecular pathways thought to underlie certain aspects of the vesicle cycle.