Researchers report that endocytosis, which was previously thought to be a random process, actually occurs in a coordinated manner through collective dynamics. The work showed how a major endocytic pathway mediated by the protein clathrin, was found to commence with periodic traveling waves of clathrin, which were coupled temporally and spatially to downstream cortical actin waves. Clathrin endocytic waves were identified as the upstream initiator of cortical actin waves.