The processes of axonal transport are in most respects identical to intracellular transport in other metazoan cells. The shapes and sizes of neurons do require that intracellular transport be amplified to an unusual degree in both the amount of material moved and the distance traveled, but the underlying molecular mechanisms appear to be shared (Brady, 1984 ; Grafstein and Forman, 1980 ; Heslop, 1975 ; Lubinska, 1975 ; Schliwa, 1984 ; Weiss, 1982 ). When considered in the context of studies of the nervous system, however, it will become apparent that experiments involving axonal transport can provide a unique window into many aspects of neurobiology. Studies of axonal transport and related phenomena can produce insights into the cellular and molecular organization of neurons, the patterns of neuronal connectivity, and the dynamics of the nervous system. Sometimes these insights will come directly from studying axonal transport itself and, in other experiments, axonal transport processes are used as a tool for labeling or experimentally manipulating a group of neurons.