Bordering Thailand, the southern part of Xayabury province is engaged in international trade and has experienced agricultural growth like nowhere else in Laos. The rapid transformation from manual slash-and-burn agriculture to mechanized, chemical-based cropping systems is often cited by Laotian authorities as a model of development. But a careful study of changes underway indicates that the reality is far less encouraging than it would appear at first. If many farmers have indeed bolstered their incomes over the last twenty years, it is no less true that some of the poorest peasants have become increasingly poorer and that the new techniques cause serious erosion, as they have not been able to prevent the expansion of cultivated areas on sloping lands.