A comprehensive series of technologies was developed for improved soil conservation, water conservation, labor use reduction, and diversification of crop production for improvement of cropping systems in undulating upland areas (100～200 m above sea level) in Northeast Thailand. 1.Alley cropping combining reforestation and crop production was effective in supplying organic matter through periodic pruning of trees, as well as preventing soil erosion in a sloping field. 2. A subsoiling treatment which cracked the upper soil layer (50～60 cm depth) was effective in trapping runoff rain water on sloping fields, which benefited the growth of crops through enhanced soil moisture availability in the dry period. 3. No-tillage crop production was effective in preventing erosion, suppressing weed proliferation and maintaining soil moisture. A no-tillage seeder which was developed in this research performed satisfactorily in sandy soil. 4. Plastic mulching was appropriate for the production of underground crops such as groundnut, by facilitating the growth and harvest of underground parts of crops while maintaining soil structure after tillage. 5. Labor saving technology for the production and incorporation of green manure crops was established through a combination of mechanized operations. 6. Mechanical weeding with inter-tillage between crops rows using a soil cultivator was effective in controlling dominant upland weeds. 7. Growth characteristics of various crops were evaluated for diversification of upland cropping, and an appropriate crop sequence was proposed together with specific production techniques.