Tremendous progress has been made since Neuron published our Primer on genetic dissection of neural circuits 10 years ago. Since then, cell-type-specific anatomical, neurophysiological, and perturbation studies have been carried out in a multitude of invertebrate and vertebrate organisms, linking neurons and circuits to behavioral functions. New methods allow systematic classification of cell types and provide genetic access to diverse neuronal types for studies of connectivity and neural coding during behavior. Here we evaluate key advances over the past decade and discuss future directions. In a sequel to their 2008 Primer on genetic dissection of neural circuits, Luo, Callaway, and Svoboda evaluate key advances over the past decade on cell-type-specific anatomical, neurophysiological, and perturbation studies to link neurons and neural circuits to behavior.