Cortical GABAergic interneurons, most of which originate in the ganglionic eminences, take distinct tangential migratory trajectories into the developing cerebral cortex. However, the ligand-receptor systems that modulate the tangential migration of distinct groups of interneurons into the emerging cerebral wall remain unclear. Here, we show that netrin-1, a diffusible guidance cue expressed along the migratory routes traversed by GABAergic interneurons, interacts with alpha3beta1 integrin to promote interneuronal migration. In vivo analysis of interneuron-specific alpha3beta1 integrin, netrin-1-deficient mice (alpha3(lox/-)Dlx5/6-CIE, netrin-1(-/-)) reveals specific deficits in the patterns of interneuronal migration along the top of the developing cortical plate, resulting in aberrant interneuronal positioning throughout the cerebral cortex and hippocampus of conditional alpha3(lox/-)Dlx5/6-CIE, netrin-1(-/-) mice. These results indicate that specific guidance mechanisms, such as netrin-1-alpha3beta1 integrin interactions, modulate distinct routes of interneuronal migration and the consequent positioning of groups of cortical interneurons in the developing cerebral cortex.