αN-catenin is a cadherin-binding protein, widely expressed in the nervous system; and it plays a crucial role in cadherin-mediated cell-cell adhesion. Here we report the effects of αN-catenin gene deficiency on brain morphogenesis. In addition to the previously reported phenotypes, we found that some of the axon tracts did not normally develop, in particular, axons of the anterior commissure failed to cross the midline, migrating, rather, to ectopic places. In restricted nuclei, a population of neurons was missing or their laminar arrangement was distorted. The ventricular structures were also deformed. These results indicate that αN-catenin has diverse roles in the organization of the central nervous system, but only in limited portions of the brain. Developmental Dynamics, 2006. © 2006 Wiley-Liss, Inc.