The Drosophila larval neuromuscular junction (NMJ) shares many structural and functional similarities to synapses in other animals, including humans. These include the basic feature of synaptic transmission, as well as the molecular mechanisms regulating the synaptic vesicle cycle. Because of its large size, easy accessibility, and the well-characterized genetics, the fly NMJ remains an excellent model system for dissecting the cellular and molecular mechanisms of synaptic transmission. This article describes the components of an electrophysiology setup, commonly referred to as an electrophysiology rig. The rig described here is based on equipment and software used in the Cold Spring Harbor Laboratory (CSHL) course "Neurobiology of Drosophila."