Fezf2 (Fezl) is a transcription factor that specifies corticospinal motor neurons (CSMN) originating from cortical layer 5b. Lodato et al. use cortical progenitor isolation from developing mouse brain and gene expression profiling to identify genes downstream of Fezf2 and demonstrate co-regulation of CSMN gene ensembles by Fezf2 in establishing CSMN cell identity.