A study was carried out to identify biological and socio-economic constraints and opportunities for livestock development in coconut plantations in Sri Lanka. One part of the study focussed on the use of participatory rural appraisal to establish felt needs of different farmer categories in terms of feeding practices. Small coconut land holders (<0.8 ha) reared livestock mainly for direct (primary) products such as milk, while large coconut holders (> 6 ha) kept livestock for indirect (secondary) benefits such as weed control, social status and security. With an increase of land area, the objectives of keeping livestock deviate from direct to indirect benefits. The total benefits either as direct or indirect were more than double the value of live weight production. The major constraint of livestock keeping for small holders in the area was small land area, lack of grazing lands and low milk price. The major issue in livestock keeping for large coconut holders was shortage of feed during dry seasons. A second part of the study tried to establish biological production potentials based on feed supply of different farmer categories. Of the two areas selected, the coconut dominant area had lower maximum live weight production or milk production than that of the paddy dominant area despite higher availability of natural grass in coconut plantations. Natural grasses in paddy fields, with a feeding value higher than that under coconuts, combined with use of rice bran led to higher live weight production in the paddy dominant area. However, in paddy dominant areas, the small size of individual land holding is more critical and causes many farmers to give up dairying. Coconut dominant areas have a potential to keep animals for indirect benefits owing to the larger size of land holdings. In general, the nutritive value of 50% of the available feeds in both areas were below maintenance level. Part of this study aimed to assess usefulness of a few 'on the shelf feeding technologies. Biologically speaking, gliricidia was found to be a potential source of feed but farmers' awareness about the potential feeding value of gliricidia was low (26%). Particularly farmers that keep livestock for indirect production (63%) found time required for collection of gliricidia a reason for low adoption of this potential feed. Farmers' awareness of urea ammonia treatment of straw was reasonable but only 3% practised this technology.