Pombe Cdc15 homology (PCH) proteins constitute an extensive protein family whose members have been found in diverse eukaryotic organisms. These proteins are characterized by the presence of several conserved sequence and structural motifs. Recent studies in yeast and mammalian cultured cells have implicated these proteins in actin-based processes, in particular, cytokinesis. Here we review the recent findings on the in vivo localization, function, and binding partners of PCH family members. We also provide new microscopy data regarding the in vivo dynamics of a budding yeast PCH protein involved in cytokinesis.