PURPOSE The purpose of this study is to describe the “New Theory” introduced by His Majesty King Bhumibol of Thailand and investigate how it is practiced in the agricultural sector. The paper describes the New Theory, how it is different from the conventional way of farming, and its benefits. The study also presents the challenges of expanding the theory into a wide scale. DESIGN/METHODOLOGY/APPROACH Qualitative research method using in-depth interviews with seven farmers to collect the primary data. The secondary data were gathered using participant observations, reference to documentation, and television documentary programs. FINDINGS The New Theory is practised at three levels focusing on the effective management of farmland to optimise its use. Level One introduces a specific way of dividing the farmland into 30:30:30:10 proportion. This level is particularly for individual benefits. Level Two and Three are for collective benefits at the community and national levels. The findings show applying the New Theory leads to better outcomes related to material, societal, cultural and environmental domains. RESEARCH LIMITATIONS/IMPLICATIONS A small number of respondents. Future research can be conducted with more respondents and with different stakeholders to gain different perspectives. PRACTICAL IMPLICATIONS The study helps to disseminate the New Theory to the farmers who are seeking for another kind of sustainable agriculture to replace conventional agriculture. SOCIAL IMPLICATIONS The results shows the New Theory can lead to food security, sustainability, and self-reliance. Consequently, this can influence farmers and general public to have a more positive attitude towards an occupation in the agricultural sector. ORIGINALITY/VALUE The new way of calculating the proportion of farmland. Also, the theory is well-known in Thailand, but little known internationally.