Seed provision for small-scale farmers deals with multiple constraints. These include, on the supply side, high seed production costs and poor adaptedness of the cultivars, and on the demand side, anticyclical demand and low and variable sales. Approaches to improve seed provision to this sector of farmers have so far not been very successful. This paper discusses how well-adapted cultivars developed through participatory plant breeding (PPB) initiatives create new opportunities for production and distribution of quality seed. It reviews supply and demand-side issues, based on research and experiences with seed production. Given better adaptation of PPB-cultivars, the diffusion of seed of PPB initiatives should not be a major bottleneck. But constraints in the provision of quality seed from cultivars that are commonly used remain and need to be addressed. Major points of attention are cost-effective seed production and distribution, high information linked transaction costs, and appropriate seed production technology. Research on these issues is needed to understand farmers' seed demand. At the same time, these issues need to be taken into account in new seed production initiatives that apply integrated approaches. Long term commitment by farmers to produce, distribute and use seeds is a condition. Even if seed production is not economically sustainable at household or organization level, farmer-based seed systems generate benefits to society as a whole that justify long term public investment to maintain them. © 2006 Springer Science+Business Media B.V.