Ecosystems may undergo nonlinear responses to stresses or perturbations. Hence there can be more than one stable state or regime. It is not known whether alternate regimes also occur in coupled social-ecologica-l systems, in which there is the potential for intricate feedbacks between natural and social processes. To find out, we investigated the management of rice paddies by Balinese farmers, where ecological processes impose constraints on the timing and spatial scale of collective action. We investigated responses to environmental and social conditions by eight traditional community irrigation systems (subaks) along a river in Bali to test the intuition that older and more demographically stable subaks function differently than those with less stable populations. Results confirm the existence of two attractors, with sharply contrasting patterns of social and ecological interactions. The transition pathway between the two basins of attraction is dominated by differences in the efficacy of sanctions and the ability of subaks to mobilize agricultural labor.