Actin filament assembly is a tightly regulated process that functions in many aspects of cell physiology. Members of the Ena/VASP (Drosophila Enabled/vasodilator-stimulated phosphoprotein) family are key players in regulating actin filament assembly, in many cases through their association with binding partners that display a particular proline-rich motif, FPPPP. Ena/VASP proteins interact with these partners via the highly conserved Ena/VASP homology 1 (EVH1) domain. The diverse array of binding partners for EVH1 domains, including cytoskeletal proteins such as zyxin, transmembrane guidance receptors such as Roundabout, and the T-cell signaling protein Fyb/SLAP, shows that these interactions are likely to be important in a number of cellular processes that require regulated actin filament assembly.