This paper investigates the ways in which different groups of people arrive at decisions regarding what tree species to plant. Data is drawn from a case study of afforestation that is taking place under the policy of Joint Forest Planning and Management in the Western Ghats of Karnataka, India. Whilst there is a clear disparity between villager and Forest Department preferences, this difference is not simply a case of Forest Department ‘science’ pitted against villagers’ ‘local knowledge’. On the one hand, both villagers and the Forest Department employ empirical evidence to inform their preferences; on the other hand, decision making goes beyond this, being influenced by a range of institutional and cultural issues. This paper identifies obstacles to a complementary working relationship between local and expert knowledge and considers the resulting management implications.