Sustainable agriculture plays an important role in achieving sustainable development goals with regard to food security and environmental conservation. Sustainable agriculture relies on sustainable farming practices that reduce greenhouse gas production, the wise use of local natural resources, and reductions in negative impacts on the environment and human health. Sustainable farming practices can be driven by various factors, such as the socio-environmental setting, socio-cognitive factors, agricultural institutions, and policy. This study used the knowledge, attitude, and practice (KAP) model to examine farmers’ knowledge, attitudes, and practices in the area of sustainable agriculture. It also considered the factors affecting farmers’ knowledge, attitudes, and practices. Two different socio-environmental contextual settings in Surin Province (a Thai-Cambodian border province) of Thailand are considered. The results show that there are differences between the two different socio-environmental contextual settings with regard to farmers’ sustainable agricultural practice perceptions, knowledge, and attitudes. Farmers’ perceptions of environmental degradation, the number of years of agricultural experience, and agricultural policy drive farmers’ attitudes and individual sustainable practices. Another major result of the study is that individual farmers’ attitudes and practices promote collective sustainable agricultural behaviors. The implication of these findings is that it is necessary to improve the learning ability of individual farmers on the environment and sustainable agricultural practices through social learning and scientific knowledge dissemination, so as to produce sustainable collective development behaviors.