Agriculture is one of the major economic sectors in Thailand, with the export-oriented agriculture promoted by the government since the 1960s playing an important role in the country’s development. While monoculture cash cropping has placed small-scale farmers at new risk, some farmers have been able to shift their farming style from cash cropping to self-sufficient farming by following His Majesty King Bhumibol Adulyadej’s philosophy of ‘Sufficiency Economy’ and ‘New Theory of Agriculture’. This chapter focuses on the practice of farming for self-sufficiency adopted in the village of Ban Na Isan, located at the east end of Chachoengsao Province in eastern Thailand, where shifting from monoculture cash cropping to farming for self-sufficiency has made the residents self-sustaining. A balanced use of farm land, crop diversification, and sustainable soil and water management has allowed farmers to be considerably self-sufficient on food and create cash income from selling extra crops. Therefore, farming for self-sufficiency has made both the life of farmers and the environment more sustainable.