Land degradation in sub-Saharan Africa reduces the land's potential productivity through soil erosion, nutrient depletion, soil moisture stress, deforestation and overgrazing. Efforts to reverse land degradation require an understanding of why it takes place and what factors govern farmers' willingness to invest in land conservation. These factors differ importantly between private and public lands. This study synthesizes results from analyses of the technological and institutional factors determining the adoption of natural resource conservation at both the household and the community levels in the northern Ethiopian region of Tigray. Using 1995-96 data from 250 Tigray farm household interviews, it first examines private land management, focusing on 1) What factors determine farmer perceptions of the severity and yield impact of soil erosion? 2) Is soil conservation profitable, and if so, then under what conditions? 3) What determines farmers' illingness to invest in soil conservation? Using 1998-99 data from a survey of 100 Tigray villages, it proceeds to examine the management of communal lands (grazing lands and woodlots), focusing on 4) What makes communities engage in collective NRM activities? 5) What determines the ffectiveness of collective NRM? At the household level, results highlight the importance of (1) the physical characteristics of plots and villages in shaping farmer perceptions, (2) the land tenure horizon and access to capital in determining willingness to invest in soil conservation. At the community level, they highlight the importance of population density, agricultural potential, as well as access to markets and external rganizations in determining community collective action and its effectiveness in establishing and managing protected grazing areas and woodlots.