Upland areas in Vietnam account for two-thirds of its natural area and one-third of its population. These uplands are characterized by heterogeneous and fragile ecosystems, a high incidence of poverty, severe deforestation and soil degradation. Rice is an important staple which is grown in the upland fields using shifting cultivation and in intensive lowland fields. The predominantly subsistence-oriented agricultural production system of these upland areas is undergoing intensification due to rapidly increasing population pressure. Changes in government policies regarding uplands and improvements in access to markets have led to the evolution of market-oriented production systems in some areas. In addition, rapid improvement in the productivity of lowland rice following decollectivization has also affected the use of upland areas. The paper examines the effect of population pressure and market access on cropping patterns, cropping intensity, the extent of commercialization of production systems, land and labor productivity, household food supply and the overall level of poverty. The analysis is based on a cross-sectional survey of 980 farm households from 33 communes of six provinces during the crop year 1997-98. It is hypothesized that (a) the cropping intensity is positively related to the population density and is negatively related to market access, (b) labor productivity in agriculture is higher in areas with better access to market, (c) upland rice occupies proportionately smaller area of upland as the size of the lowland holding increases, and (d) the extent of food shortage depends on land and labor endowments as well as the access to markets. Reduced-form models were used to investigate these hypotheses. Cropping intensity was found to be higher in communes with a higher population density supporting the Boserupian hypothesis. Market access, which was specified as a dummy variable (low access and high access), affected labor productivity and cash income positively. Despite these positive effects, the agricultural production system was found to be predominantly subsistence-oriented with farmers striving to achieve food self-sufficiency even in areas where a lot of cash crop is grown. The proportionate area under upland rice was found to be related negatively with the size of the lowland holding indicating that an improvement in lowland productivity can help reduce the intensification pressure in the upland. Farmers with better access to market and with larger farms were found to have a lower incidence of food shortage than farmers with limited access to markets and with smaller farms. A simulation model was developed to project the likely effect of continued increase in population pressure on food production, labor absorption in agriculture, calorie consumption per capita and the extent of poverty. A simple life table was used to project the population by sex and age group for the next 20 years. The effect of rising population pressure on food production was simulated assuming that the current agricultural productivity of different land/labor quartiles applies to the households as they move across the quartile groups. The static projection indicated that while the labor force will increase by 75% in 20 years, labor use in crop production will increase by only 9%, thus showing the need to expand labor absorption in the non-crop sector. With the existing technology, crop production will increase by only 5% of its current value leading to a dramatic decline in per capita food supply. The growth in rice yield (both upland and lowland) of at least 2% per annum is needed to maintain the current per capita calorie intake. An improvement in the upland rice yield was found to be an important strategy in reducing the poverty of the low-income quartile group that depends mostly on upland rice. Given the size of the population growth, the overall reduction in poverty will require an expansion of employment in the non-crop and non-farm sectors. The paper concludes with recommendations that include (a) further expansion of market access and development of more effective marketing institutions, (b) a regionally differentiated approach to agricultural diversification that recognizes the environmental diversity, (c) improvements in food production technology, (d) expansion of income-generating activities such as agro-processing and (e) more effective population control programs.