words)Caveolae are specialized domains of the vertebrate cell surface with a well-defined morphology and crucial roles in cell migration and mechanoprotection. Unique compositions of proteins and lipids determine membrane architectures. The precise caveolar lipid profile and the roles of the major caveolar structural proteins, caveolins and cavins, in selectively sorting lipids have not been defined. Here we used quantitative nanoscale lipid mapping together with molecular dynamic simulations to define the caveolar lipid profile. We show that caveolin1 (CAV1) and cavin1 individually sort distinct plasma membrane lipids. Intact caveolar structures composed of both CAV1 and cavin1 further generate a unique lipid nanoenvironment. The caveolar lipid sorting capability includes selectivities for lipid headgroups and acyl chains. Because lipid headgroup metabolism and acyl chain remodelling are tightly regulated, this selective lipid sorting may allow caveolae to act as transit hubs to direct communications among lipid metabolism, vesicular trafficking and signalling.Caveolae are a striking morphological feature of the plasma membrane of many vertebrate cells. Caveolae have been implicated in mechanoprotection, endocytosis, signal transduction and lipid regulation 1-6 . The characteristic morphology of caveolae, with a bulb connected to the plasma membrane by a highly-curved neck, is generated by integral membrane proteins termed caveolins and by lipid binding peripheral membrane proteins, the cavins 7-14 .Specifically, caveolin-1 (CAV1) and caveolin-3 (CAV3, in striated muscle) and cavin1 (or polymerase I and transcript release factor, PTRF) are essential for caveola formation 7,10 .Another set of key caveolar components comprise the plasma membrane (PM) lipids. While biophysical studies have consistently suggested that the lateral distribution of lipids determines and/or responds to changing membrane morphology, our understanding of the lipid composition of caveolae and how this contributes to caveola formation, function, and disassembly, is still relatively primitive. A detailed molecular understanding of the lipid constituents of caveolae, defined both by their headgroups and acyl chains, is crucial for understanding the formation of caveolae, as well as their disassembly, processes that are crucial for caveola function. Moreover, caveolae can provide a paradigm for understanding how local concentrations of specific lipid species contribute to membrane morphogenesis.