Correct distal tip cell (DTC) migration in the nematode C. elegans requires sensing soluble and matrix cues, remodeling extracellular matrix, and signaling through conserved integrin and netrin pathways. The DTC executes a complex path and coordinates its migration with the developmental stages of larval morphogenesis. This chapter outlines a method for investigating DTC migration in C. elegans using feeding RNA interference (RNAi) and light microscopy. To deplete a candidate gene of interest, nematode eggs are added to plates seeded with RNAi-inducing bacterial lawns. The animals hatch and begin to eat the RNAi bacteria, releasing dsRNA and causing the targeted gene to be depleted during larval development. Positions of migratory cells are monitored in larvae and young adults using differential interference contrast (DIC) and epifluorescence microscopy.