Continuing degradation of the environment and the cumulating food, energy, water and financial crises have led to a situation where many people’s access to sufficient, nutritious food is affected as well as their livelihoods, income, and ultimate food and nutrition security. In the wake of these stresses and crises, there is an emerging interest to find efficient, easily accessible and sustainable approaches that can address these crises. One candidate for this is the System of Rice Intensification (SRI) with its “less can produce more” prescription. A regional collaborative project currently underway is being implemented in rainfed areas of the Lower Mekong River Basin (LMB) countries. This involves smallholder rice farmers, researchers, extension personnel, and development professionals, together with staff of relevant government ministries (http://www.sri-lmb.ait.asia/). The project objective is to produce healthier and profitable rice crops under rainfed conditions using SRI methods, evaluated and refined through farmers’ participatory action research (FPAR). As part of the action-research, more than 120 sets of field experiments have been carried out at 60 FPAR sites in Cambodia and Thailand, directly involving 3600 farmers. The experiments have ranged from the integration of many SRI principles with farmers’ current local practices or improved practices which was termed as “SRI-transition” to full demonstrations and assessments of SRI methodology, i.e., SRI demonstration. The initial calculation of yields has showed an average paddy yield of 5.03 t/ha with SRI-transition, whereas with SRI-demonstration the average yield was 6.41 t/ha. These yields were 60 and 100% higher than the average baseline yield in the region, 3.14 t/ha, for the same farmers and same locales. Productivity gains (dollars gained/dollars spent per ha) were calculated for both rainfed and irrigated production areas. In comparative terms, the economic gains for farmers were found to be higher in rainfed areas when using the new methods. This paper addresses the potential of new strategies to promote food security in rainfed areas in the LMB region by managing household and natural resources more productively.