Rho proteins, including RhoA, Rac1 and Cdc42, are members of the Ras superfamily of monomeric GTP-binding proteins, which are well-known regulators of the cytoskeleton. Numerous studies have shown that an intact cytoskeleton is required for cell cycle progression through G1 phase as well as mitosis and cytokinesis. Because of their role in both cytoskeletal rearrangement and mitogenic signaling, Rho family proteins are key mediators of cell cycle progression. In this paper, we review the current state of knowledge concerning the Rho-dependent signaling pathways that regulate the expression of cell cycle regulatory proteins required for G1 phase progression and S phase entry.