Genetic approaches in flies and worms continue to dissect the intricate molecular machinery of chemical synapses. Investigations carried out in the last year provide important new insights into the development and modulation of the presynaptic active zones and postsynaptic receptor fields mediating synaptic function. Mutant screens have identified overlapping gene classes mediating synaptogenesis. The leucocyte common antigen-related receptor tyrosine phosphatase interacts with liprin in the formation of the active zone. Spectrins are essential for the spatial restriction of synaptic proteins to define active zones. Glutamate acts as a negative regulator of its cognate postsynaptic receptor to sculpt receptor field size. Finally, protein translation and degradation regulation emerge as possible key regulators of synaptic efficacy.