Food security problems are major issues in developing countries, especially under the conditions of restricted farm resources and environmental degradation. The re-allocation of existing farm resources in the upland in order to reach a production of maximum output under given technologies and the estimated value of the technical efficiency have been important information for this purpose. The objective of this study, therefore, was to measure the technical efficiency of upland rice production in Thailand. The identification of key factors to improve the technical efficiency was additionally carried out. A stochastic frontier approach with the Cobb-Douglas production function was applied. Data used in this study has been drawn from 181 farmers. The findings showed that on average the technical efficiency was 0.70 and the rank of its value varied from 0.22 to 0.94. A significant factor affecting the technical efficiency has been support in terms of transforming knowledge through a training program on upland rice production. Farmers, who grew upland rice for both household consumption and for commercial purposes, had a better performance than those who grew upland rice only for home consumption.