The low rate of technology adoption has long been a key constraint on improving productivity, income and yields in farming, particularly in developing countries where market-based systems of production are not well developed, the subsistence economy remains strong, land is held under communal tenure and family labour is the backbone of production. We examine four case studies of technology adoption to explore key socio-economic factors facilitating or constraining adoption. Our case studies cover an array of adoption situations from different parts of the developing world: 1. The socio-cultural barriers to the adoption of new technologies to control Cocoa Pod Borer in Papua New Guinea; 2. The role of land pressure on differential adoption rates of cocoassie yams amongst ethnic groups in Ivory Coast; 3. Past agricultural practices and their influence on adoption of a new planting pattern and selected oil palm planting material in Cameroon; 4. Taking account of gender relations to facilitate successful adoption of a new oil palm initiative for women smallholders in Papua New Guinea.