The complete known anatomical connections of C. elegans nervous system have provided researchers ample opportunities to discover fundamental principles underlying neuronal development. Transgenic labeling with fluorescent proteins in neuronal cells has had an unparalleled impact on our ability to visualize cellular architecture and dynamics. In this chapter, we summarize the common methods and guidelines for dissecting the molecular and cellular mechanisms controlling nervous system formation. We end with a brief description of several applications that illustrate the use of these methods.