The purpose of the study was to assess the impact of Farming Systems Research/Extension (FSR/E), differential access to agricultural support services and human capital endowment on farm-households' adoption of agricultural innovations in the Middle-Belt region of Nigeria. The research was conducted within a World Bank-funded Agricultural Development Project located in Niger State, where the International Institute of Tropical agriculture (IITA) has been implementing FSR activities to develop and test appropriate technologies for the inland valleys' farming systems;Data collection involved a triangulation approach consisting of non-participant observation, qualitative group interviews, and individual interviews with 513 farm-households' heads. Data were analyzed using frequencies, means, t-test, chi-square and multiple regression;The study found that a majority of the respondents were resource-poor subsistence producers. Farmers' adoption of the recommended technological package for rice, corn, sorghum and cowpea, was piece-meal and selective. While, over 80% of the respondents had adopted fertilizer, the adoption rates for improved varieties, seed dressing, herbicides, and insecticides were less impressive;Using Biggs's classification (1989), farmers' participation in the project was limited to either the contract or consultative mode. Chi-square and t-test analyses showed that FSR participants achieved a higher rate of innovation adoption than non-participants. Multiple regression analysis showed that variables characteristic of the institutional constraint model, and farmers' perceptions of the relative advantage of the recommended innovations were the best predictors of farmers' adoption. However, classical diffusion variables such as farm size, education, income, and age, emerged as poor predictors;It was concluded that in order for FSR/E to remain a viable approach to sustainable agricultural development in the third world countries, greater emphasis must be placed on enhancing farmers' participation, and on the development of appropriate institutional linkages among research, the farming community, extension services, and other agricultural development agencies.