The 14-3-3 proteins constitute a family of dimeric proteins that are involved in many cellular functions. At least two mammalian 14-3-3 proteins can form heterodimers and the approximate regions important for dimerization have been identified. In this study, we demonstrate that eight Arabidopsis and one maize 14-3-3 protein can dimerize with each other and with themselves. Native gel Western analysis of Arabidopsis cell extract also suggests the presence of 14-3-3 heterodimers in vivo. Finally, we identified the domains of one 14-3-3 protein that are sufficient for homodimerization and heterodimerization. These data support the hypothesis that evolutionarily divergent 14-3-3 proteins can interact with each other to form diverse molecular modulators or adapters in signaling pathways.