This paper analyzes the dramatic increases in rice output and productivity in Vietnam due largely to market reform, inducing farmers to work harder and use land more efficiently. The reform process is captured through changes in effort variables and a decomposition of total factor productivity (TFP) due to enhanced incentives for two main reform periods: output contracts(1981-87) and trade liberalization (1988-94). The results show that the more extensive is market reform the larger the increase in TFP and the share of TFP growth due to incentive effects, suggesting that more competitive markets and secure property rights matter greatly.However, in the post-reform period (1995-99), the incentive component of TFP dissipates as a result of falls in the price of rice and slow increases in input prices, especially for hired labour, fertilizer and capital. A stochastic production frontier is estimated to determine what farm-specific factors limit efficiency gains. Results show that farms in the main rice growing regions, those with larger farm size and farms with a higher proportion of rice land ploughed by tractor are more efficient, suggesting the need for additional reforms to augment productvity. In particular, the requirement that rice be grown in every province in Vietnam, restrictions on farm size(especially in the north) and the slow development of rural credit markets for capital and land are seen to restrict the level and growth of efficiency substantially.