In the Iate 80s, the Socialist Republic of Vietnam embarked on bold economic liberalization policies. The ensuing market, price, credit, and land tenure reforms allowed very reactive small farmers to use new technologies and to improve their livelihoods thanks to a dramatic agricultural growth, especially in irrigated rice production. This was particularly the case in the Mekong Delta and this article analyzes the impact of the economic liberalization reforms on this crucial agricultural system. The process of rice intensification is explained in detail, and an analysis of the closely related dynamics of diversification into non-rice activities is also provided. The intensification of rice-based production systems with more fixed capital, working capital, and labor led to an increase in family incomes. But the evolutionary pathways of farming households reveal that, depending on their initial endowment in productive resources, the pace of capital accumulation has been unequal among farmers. Consequently, economic reforms are leading to an increased differentiation among farming households in terms of types of production system and income level. At a time of increasing use of chemical inputs and renewable natural resources, and as social inequalities lead to labor migration, several key technological, environmental, and socioeconomic issues regarding the sustainability of rice intensification and agricultural diversification processes are discussed.