Vasodilator-stimulated phosphoprotein (VASP) is a member of actin regulatory proteins implicated in platelet adhesion. Ena/VASP proteins are conserved regulators of actin dynamics that have important roles in several physiological processes such as morphogenesis, axon guidance, endothelial barrier function, and cancer cell invasion and metastasis. Ena/VASP proteins act as actin polymerases that drive the processive elongation of filament barbed ends in membrane protrusions or at the surface of bacterial pathogens. Ena/VASP tetramers are processive actin elongation factors that localize to diverse F-actin networks composed of filaments bundled by different cross-linking proteins, such as filopodia (fascin), lamellipodia (fimbrin), and stress fibers (α-actinin). Also, phosphorylation of VASP is utilized for the assessment of platelet reactivity in patients treated with P2Y12 receptor antagonists, a class of antiplatelet agents.