Since the discoveries of class I myosins, the first non-muscle myosins, about 30 years ago, their history has been linked both to the organization and working of actin filaments and to their connection to membranes, especially the plasmalemma. Indeed, the early biochemical characterization highlighted the capacity of these mechanochemical enzymes to crosslink actin filaments and to bind phospholipids. Recent findings shed new light on these relationships and reveal a more active role of class I myosins in regulating the spatial and temporal nucleation and elongation of actin filament in close proximity of membrane sites determined by signalling and cell polarity mechanisms. The understanding of the role of the actin cytoskeleton in cell motility has recently made a giant leap forward with the discovery and dissection of the major actin nucleator, the Arp2/3 complex, and some of its activators. To investigate the molecular and cellular bases of the integration of myosin motor activity and actin dynamics in cortical management and cell motility, we make use of a genetically and biochemically tractable model organism, Dictyostelium discoideum. As the components of these complex machineries are evolutionarily conserved, their molecular and cellular dissection in D. discoideum is directly relevant to unravel their functional importance in higher organisms.