In mammals there are two types of adipocytes with opposing functions. Brown adipocytes are characterized by a high number of mitochondria and are specialized for heat production (thermogenesis), expressing thermogenic genes such as UCP1 (uncoupling protein 1). White adipocytes, on the other hand, store energy. Although many key regulators in the differentiation of white adipocytes have been established, our current knowledge on the same proteins in brown adipogenesis is lagging behind. One example is Pref-1 (pre-adipocyte factor-1), which maintains white pre-adipocytes in an undifferentiated state, but is only poorly characterized in the brown pre-adipocyte lineage. In this issue of the Biochemical Journal, Armengol et al. now shed new light on the role and regulation of Pref-1 in brown pre-adipocytes. First, Pref-1 specifically inhibits the thermogenic gene programme in brown pre-adipocytes. Secondly, they identified the transcription factor C/EBPδ (CCAAT/enhancer-binding protein δ) as a direct positive regulator of Pref-1 expression, whereas this protein does not fulfil this role in white adipogenesis. Taken together, these findings indicate that specific manipulation of brown adipocyte differentiation and/or function without interfering with their white adipocyte counterparts may be possible, which may open up new therapeutic ways to combat obesity-associated health problems.