Pii: S0305-750x(00)00063-2

Ð An analytical construct of social capital is presented, followed by a case study from Sri Lanka. There, farmer organizations were established in the Gal Oya irrigation scheme in the early 1980s with a combination of roles, rules, norms and values that supported mutually bene®cial collective action. This produced measurable improvements in system performance and eciency. In the 1997 dry season, after farmers were told there was not enough water in the reservoir to grow a rice crop, they achieved through their organizations a better-than-average harvest from 65,000 acres by ecient and equitable distribution. Ethnic cooperation was demonstrated by upstream Sinhalese farmers sharing water with downstream Tamil farmers. Ó 2000 Elsevier Science Ltd. All rights reserved.