TAF10 (formerly TAFII30), is a component of TFIID and the TATA box-binding protein (TBP)-free TAF-containing complexes (TFTC/PCAF/STAGA). To investigate the physiological function of TAF10, we disrupted its gene in mice by using a Cre recombinase/LoxP strategy. Interestingly, no TAF10−/− animals were born from intercrosses of TAF10+/− mice, indicating that TAF10 is required for embryogenesis. TAF10−/− embryos developed to the blastocyst stage, implanted, but died shortly after ca. 5.5 days postcoitus. Surprisingly, trophoblast cells from TAF10−/− blastocysts were viable, whereas inner cell mass cells failed to survive, highlighting that TAF10 is not generally required for transcription in all cells. TAF10-deficient cells express normal levels of TBP and TAFs other than TAF10 but contain only partially formed TFIID, are endocycle arrested, and have undetectable levels of transcription. Thus, our results demonstrate that TAF10 is required for TFIID stability, cell cycle progression, and transcription in the early mouse embryo.