Mounting evidence supports that RAC/ROP GTPases are central regulators for diverse signaling pathways for plant growth, development, and interactions with the environment. Their regulatory activities for key intracellular process, such as control of actin dynamics, membrane trafficking, and several hormone signal transduction pathways, suggest inevitable functional roles for RAC/ROPs in regulating cellular activities that underlie important growth and developmental events, especially those that involve cellular and morphological asymmetry. RAC/ROPs are well established as a regulator for the two most polarized cell growth processes in plants, pollen tube tip growth, and root hair elongation, and are known to be crucial for the differentiation of leaf epidermal cell patterning, which depends substantially on differential cell expansion around its periphery and asymmetric cell division. We focus here on discussing recent findings, especially those that relate to upstream regulators and downstream effectors of RAC/ROPs that illuminate how these small GTPases and their interactors together contribute to polarity-dependent processes in plants.