Neurog1 (Ngn1, Neurod3, neurogenin1) is a basic helix-loop-helix (bHLH) transcription factor essential for neuronal differentiation and subtype specification during embryogenesis. Due to the transient expression of Neurog1 and extensive migration of neuronal precursors, it has been challenging to understand the full complement of Neurog1 lineage cells throughout the central nervous system (CNS). Here we labeled and followed Neurog1 lineages using inducible Cre-flox recombination systems with Neurog1-Cre and Neurog1-CreERT2 BAC (bacterial artificial chromosome) transgenic mice. Neurog1 lineage cells are restricted to neuronal fates and contribute to diverse but discrete populations in each brain region. In the forebrain, Neurog1 lineages include mitral cells and glutamatergic interneurons in the olfactory bulb, pyramidal and granule neurons in the hippocampus, and pyramidal cells in the cortex. In addition, most of the thalamus, but not the hypothalamus, arises from Neurog1 progenitors. Although Neurog1 lineages are largely restricted to glutamatergic neurons, there are multiple exceptions including Purkinje cells and other GABAergic neurons in the cerebellum. This study provides the first overview of the spatiotemporal fate map of Neurog1 lineages in the CNS. J. Comp. Neurol. 519:1355–1370, 2011. © 2010 Wiley-Liss, Inc.