SignificanceCaenorhabditis elegansis a round worm that has been successfully used to study synaptic transmission, the process by which neurons communicate with targets cells in the nervous system through the release of chemical neurotransmitters. Many synaptic proteins involved in this release process are highly conserved with some species-specific variations in individual components. Here, we examined how theC. elegansprotein, clarinet (CLA-1), an elusive member of the Piccolo, Fife and Rab3-interactingmolecule (Rim) protein family, fits into the organization and function of synaptic release sites in the worm. Using CRISPR/Cas-9 to endogenously tag key synaptic players, we determined the functional hierarchy of theseC. eleganssynaptic proteins and provide insights into conserved design principles that govern nervous system function.