Thailand’s manufacturing sector is characterised by considerable resource misallocation compared with this sector in other countries, and the problem may extend to its agricultural sector as well. Using detailed household-level data on rice production from the 2013 Agricultural Census, this paper examines resource misallocation across farms in Thailand and its effect on the country’s aggregate productivity in rice farming. I find that the marginal products of land and capital were largely dispersed, which is an indication of significant resource misallocation. I further estimate that reallocation of resources could increase aggregate output and productivity by approximately a factor of 1.67. This potential gain is not small, but it is smaller than that predicted in other studies for the Thai manufacturing sector and the Malawian agricultural sector, a result suggesting that the Thai rice farming sector is relatively less plagued by resource misallocation. Other developing countries may encounter similar degrees of misallocation in their agricultural sectors. I also find that an effective reallocation policy cannot involve simply reducing the landholdings of large landholders but rather supports highproductivity farmers to have more land and capital.