AbstractSummary: The cerebellum maintains balance and orientation, refines motor action, stores motor memories, and contributes to the timing aspects of cognition. We generated two mouse lines for making Cre recombinase‐mediated gene disruptions largely confined to adult cerebellar granule cells. For this purpose we chose the GABAA receptor α6 subunit gene, whose expression marks this cell type. Here we describe mouse lines expressing Cre recombinase generated by 1) Cre knocked into the native α6 subunit gene by homologous recombination in embryonic stem cells; and 2) Cre recombined into an α6 subunit gene carried on a bacterial artificial chromosome (BAC) genomic clone. The fidelity of Cre expression was tested by crossing the mouse lines with the ROSA26 reporter mice. The particular α6BAC clone we identified will be valuable for delivering other gene products to cerebellar granule cells. genesis 36:97–103, 2003. © 2003 Wiley‐Liss, Inc.