We test an emerging theory of the forest transition using the case of Vietnam. In the early 1990s, decollectivisation of agriculture, allocation of forestry land to households, and the development of market networks transformed land use in the mountains of Vietnam, leading to an increase in forest area. We used census and geographic data covering the whole country at a fine level of aggregation to build a spatial lag regression model of reforestation. We separated natural forest regrowth from the increase in plantation forests. The forest transition theory distinguishes between the forest scarcity and economic development paths. Our study suggests that the forest scarcity path was in part at work in Vietnam: new policies allocating forestry land to households, local scarcity of forest products, and development of remote demand for timber contributed to forest cover increases. The evidence regarding the economic development path are more ambiguous, as there was no depopulation or agricultural decline in marginal regions. We propose a third forest transition path that better corresponds to Vietnam's situation: a smallholder agricultural intensification path. In marginal regions, land scarcity associated with population growth, land degradation, and political restrictions led to, on one hand, a decline in cultivation on hillsides followed by reforestation and, on the other hand, an increase in labour inputs on the plots with the highest agro-ecological potential. The development of markets for agricultural inputs and outputs did also contribute to reforestation by raising agricultural productivity in mountain paddies and maize fields. This reinforced the concentration of agriculture on the most suitable land. (C) 2007 Elsevier Ltd. All rights reserved.