Peroxisome proliferator-activated receptors (PPARs) regulate genes involved in lipid metabolism and adipocyte differentiation. Steroid receptor coactivator-1 (SRC-1) and PPAR-binding protein (PBP) interact with PPARγ and act as coactivators to enhance ligand-dependent transcription. We report here that PPAR-γ, SRC-1, and PBP are differentially expressed in the brown fat, transitional epithelium of the urinary bladder, colonic mucosa, and mammary epithelium of the adult mouse. PPARγ and PBP are expressed in the transitional epithelium of urinary bladder and in brown adipose tissue, but not SRC-1. In the colonic mucosa, PPARγ expression occurs throughout the villi, whereas the expression of both SRC-1 and PBP is confined mostly to the crypts. The expression of both SRC-1 and PBP is prominent in the breast epithelium of nonpregnant, pregnant, and lactating mice, whereas PPARγ expression appeared prominent during lactation. During early embryonic development, PPARγ, SRC-1, and PBP are differentially expressed, with only limited cell types displaying overlapping expression. PPARγ and PBP expression overlapped in the brown fat and urogenital sinus at stage E15.5 of embryogenesis, whereas SRC-1 expression occurred mostly in neuroepithelium and cartilage between stages E9.5 and E13.5 of embryogenesis.