During neuronal migration, forces generated by cytoplasmic dynein yank on microtubules extending from the centrosome into the leading process and move the nucleus along microtubules that extend behind the centrosome. Scaffolds such as radial glia guide neuronal migration outward from the ventricles, but little is known about the internal machinery that ensures that the soma migrates along its proper path rather than moving backward or off the path. Here we report that depletion of KIFC1, a minus-end-directed kinesin called HSET in humans, causes neurons to migrate off their appropriate path, suggesting that this molecular motor is what ensures fidelity of the trajectory of migration. For these studies, we used rat migratory neurons in vitro and developing mouse brain in vivo , together with RNA interference and ectopic expression of mutant forms of KIFC1. We found that crosslinking of microtubules into a non-sliding mode by KIFC1 is necessary for dynein-driven forces to achieve sufficient traction to thrus...