Nepal is primarily an agrarian country: 88% of the population lives in rural areas and 80% of the adult rural population is engaged in agriculture. The country is among the poorest in the world, with an annual per capita GDP of less than US$250. Maize is the most important food crop in the hills of Nepal, where it is grown mainly by small-scale, resource-poor farmers. The crop is currently cultivated on approximately 0.85 million ha with an average yield of 1.8 t/ha, 78% of this is grown in the hills. The Hill Maize Research Project (HMRP) funded by the Swiss Agency for Development and Cooperation (SDC), has been working in a participatory mode with government and non-government organizations with the aim to develop, identify, validate and disseminate maize technologies for the benefit of poor farmers in the hills of Nepal. The project balances basic and adaptive research and emphasizes gender equity and social inclusion, multiplying seed of varieties selected by farmers in participatory varietal selection trials, community based seed production, and other participatory approaches. Project's results show that quality seed of new, improved maize varieties alone can increase maize productivity by at least 20%. Farmers can obtain significant net profits by intercropping cash crops with maize. Sowing two maize plants per hill is better for vegetable intercropping and reducing women's work. Integrated plant nutrient systems (IPNS) are suitable for sustainable maize production and the application of lime @ 2 t/ha are most beneficial. Farmers who adopted HMRP technologies significantly improved their food security, with greater involvement of poor women and excluded groups. This paper discusses the participatory research methodologies that have been used to increase food security and improve the livelihoods of poor maize farmers in the hills of Nepal.