In Southeast Asia there are many serious problems of agricultural sustainability, associated with all of the major agroecosystems. But the sloping uplands are geographically the most extensive ecosystems, and the most threatened. The nonsustainability of land-use systems in the uplands is associated with increasing populations of subsistence farm families cultivating infertile sloping soils, accelerating land degradation and soil erosion, the impending loss of most tropical hardwood forest, and the failure of reforestation. Inequitable and insecure access to land resources exacerbates the tendency toward inappropriate land use. More productive and sustainable land-use systems must be developed under conditions of severe social and economic constraints. The crisis appears largely intractable unless systematically and innovatively addressed. The problems of upland resource base deterioration extend across all national frontiers in the region, but they are only now beginning to be grappled with by the respective governments. Within each country the domain of the uplands is usually a complex division of responsibilities among the forestry department and the agriculture department. This greatly complicates technology generation, land tenure, and the delivery of infrastructure and services in these ecosystems. The objectives of this chapter are: First, to characterize the humid sloping uplands of Southeast Asia as a distinct ecosystem, and to convey a sense of the problems of generating sustainable agricultural systems for them; second, to discuss the critical agricultural sustainability issues, and the technologies being evolved to meet those needs; third, to discuss the unique ways in which research must be organized, managed, and located, in order to address the problems comprehensively. Finally, I will propose a more comprehensive international effort to address sustainable land-use systems in the acid sloping upland ecosystems in Southeast Asia.