Many households in underdeveloped and developing countries still suffer from food insecurity, which is unreliable access to a sufficient quantity of nutritious food. It is a major cause of malnutrition and undernourishment. Thailand is a food surplus country but food accessibility, particularly among rice-farming households, is often problematical. Consequently, their energy consumption is often lower than national minimum dietary energy requirements and they suffer from undernourishment. To provide policy recommendations to support rice-farming households, this study identifies the determinants of their food security using a logit model. Household food security is a binary variable: it is classified as food-secure or food-insecure using a minimum dietary energy requirement threshold of 2,100 kcal/adult equivalent/day. The analysis draws on 2,871 households from Thailand’s SocioEconomic Survey (SES) data in 2011. It finds that 57% of total households are food-secure, while 43% are food-insecure. Key findings are as follows. First, those households with relatively better educated heads are more likely to be food-secure than those with lower educational levels. Second, increases in household income or food expenditure lead to higher probabilities of food security. Third, households that produce more food for own consumption are more likely to be food-secure than those which sell a higher proportion of what they produce. Fourth, livestock ownership or increases in farm inputs, such as family labor, farm size and fertilizer, improve the probability of food security. However, increases in household size, the dependency ratio, and total household expenditure result in a lower probability of households being food security. The findings therefore suggest that food insecurity can be alleviated by the extension of provisions towards integrated farming and self-sufficiency, better family planning programs and child care, better education, and managing household income and expenditure for food consumption. In addition, increases in farm size, use of family labor and use of fertilizer can further enhance food security.