Over the last two decades, the Drosophila larval neuromuscular junction has gained immense popularity as a model system for the study of synaptic development, function, and plasticity. With this model, it is easy to visualize synapses and manipulate the system genetically with a high degree of temporal and spatial control, which makes it ideal for resolving problems in synaptic physiology and development. A number of different techniques have been used to dissect third-instar larval preparations to expose the body-wall muscles. Here, we describe a procedure that uses magnetic chambers and pins to allow for fine control in spreading the larval body wall.