Fatty acids are a major energy source for tissues such as the liver, heart and skeletal muscle. When not metabolically required, the molecules are stored in intracellular compartments called lipid droplets. These storage sites originate from distinct regions of the ER, where the lipids are synthesised and then aggregate in the hydrophobic core of the ER membrane. In the current biogenesis model, the droplet is then thought to bud from the ER and form an individual organelle surrounded by a membrane monolayer. However, experimental data supporting this model are rare. In an attempt to clarify the steps involved in lipid droplet biogenesis, Roger Schneiter and colleagues (p. 2424) now discover that, instead of budding from the ER, lipid droplets remain in contact and exchange membrane proteins with the organelle. By creating yeast strains in which transcription of the genes encoding two enzymes catalysing triacylglycerol formation can be induced artificially, the authors show that lipid droplets are indeed formed at the ER membrane and that lipid droplet marker proteins are inserted at this site. Furthermore, these membrane proteins move bidirectionally between the ER membrane and lipid droplets, most likely by a diffusion-driven mechanism. These findings thus suggest that, instead of constituting an individual organelle, lipid droplets remain functionally connected to the ER.