Public sector provision of improved seeds in developing countries has often fallen foul of government failure, while commercial seed supply has faced unusually high transactions costs and some market failure. Both have met difficulties in providing appropriate seed for marginal farm lands. Into the gap have come nongovernmental organisations (NGOs), most of them involved in small-scale seed multiplication and distribution. Evidence from a review of 19 NGO programs suggests that their seed activities operate on a small scale, sometimes with little distinctive technical competence, and tend to ape other formal sector methods. Above all, they face a challenge in making their efforts sustainable: the most promising avenue seems to lie in their supporting the growth of small seed production and distribution enterprises at farm and village level.