Significance: High levels of brown/beige fat activity protects animals against metabolic disease, but there has been little known about the precursor cells that mediate the expansion of brown or beige fat. We discovered that early B-cell factor 2 (Ebf2), a transcription factor, is selectively expressed in brown and beige fat cell precursors. Through purification of Ebf2 ⁺ cells, we identified a gene profile of brown fat precursors that can be used to distinguish these cells from other developmentally related cell types. Importantly, Ebf2 was also found to regulate the gene expression profile of brown fat precursor cells. Taken together, this study identifies Ebf2 as a highly specific marker of brown and beige preadipose cells and reveals that Ebf2 functions to control brown preadipose cell identity.