White fat progenitors reside in the adipose vasculature, functioning as a progenitor niche that supports adipocyte development. This study used genetically marked mice to isolate and analyze adipogenic progenitors. It was found that most adipocytes originate from a pre-existing pool of proliferating progenitors, which are located in the mural cell compartment of the adipose vasculature but not in other tissues. These progenitors are capable of proliferation and contribute to the rapid expansion of the adipose lineage during the first postnatal month. The adipose stromal-vascular fraction (SVF) contains PPARγ-expressing cells that are capable of adipogenesis. These cells were shown to be distinct from adipocytes and other SV cells, with a unique molecular signature. They were also found to be capable of forming adipocytes when transplanted into nude mice. The study further demonstrated that these progenitors reside in the adipose vasculature and are distinct from mural cells in other tissues. The results suggest that the adipose vasculature functions as a progenitor niche that provides signals for adipocyte development. The findings have important implications for understanding adipocyte biology and may lead to new therapeutic approaches for obesity and diabetes.White fat progenitors reside in the adipose vasculature, functioning as a progenitor niche that supports adipocyte development. This study used genetically marked mice to isolate and analyze adipogenic progenitors. It was found that most adipocytes originate from a pre-existing pool of proliferating progenitors, which are located in the mural cell compartment of the adipose vasculature but not in other tissues. These progenitors are capable of proliferation and contribute to the rapid expansion of the adipose lineage during the first postnatal month. The adipose stromal-vascular fraction (SVF) contains PPARγ-expressing cells that are capable of adipogenesis. These cells were shown to be distinct from adipocytes and other SV cells, with a unique molecular signature. They were also found to be capable of forming adipocytes when transplanted into nude mice. The study further demonstrated that these progenitors reside in the adipose vasculature and are distinct from mural cells in other tissues. The results suggest that the adipose vasculature functions as a progenitor niche that provides signals for adipocyte development. The findings have important implications for understanding adipocyte biology and may lead to new therapeutic approaches for obesity and diabetes.