Clathrin-mediated endocytosis is a multistep process which requires interaction between a number of conserved proteins. We have cloned two mammalian genes which code for a number of endocytic adaptor proteins. Two of these proteins, termed Ese1 and Ese2, contain two N-terminal EH domains, a central coiled-coil domain and five C-terminal SH3 domains. Ese1 is constitutively associated with Eps15 proteins to form a complex with at least 14 protein–protein interaction surfaces. Yeast two-hybrid assays have revealed that Ese1 EH and SH3 domains bind epsin family proteins and dynamin, respectively. Overexpression of Ese1 is sufficient to block clathrin-mediated endocytosis in cultured cells, presumably through disruption of higher order protein complexes, which are assembled on the endogenous Ese1–Eps15 scaffold. The Ese1–Eps15 scaffold therefore links dynamin, epsin and other endocytic pathway components.