In the countries of the Commonwealth Caribbean there has been a dramatic expansion in drug demand reduction (DDR) programmes over the past decade. Often drawing on models originating in the countries providing the funding in North America or Europe, these activities have often been inadequately monitored and rarely evaluated. The absence of routine evaluation, combined with a lack of qualitative research, has left large gaps in the evidence base of Caribbean drug demand reduction policy. Dissatisfaction with outcomes among funders, and demands by Caribbean professionals to move towards an evidence-based drugs policy initiated a joint training programme between the Caribbean Harm Reduction Coalition and DrugScope. The objective was to help a change in culture and promote critical evaluation. At the outset there was a clear difficulty in selecting participants from among the well-organized, but sometimes rigid, state sector and financially vulnerable, but flexible, Non-Governmental Organizations (NGOs). The key activity was training a cadre of professionals to evaluate ongoing demand reduction activities in the region. Initial concerns over the long-term benefits of training NGO personnel were dispelled by their lower attrition and higher assignment completion rates. The state sector participants retained in the programme did, however, score higher in completing the evaluation course reports. Significantly, state-sector evaluations were mainly concerned with processes, while NGO participants focused on outcomes that reflected the division of responsibilities between programme management and the provision of client services. The resulting mix confirmed the value of selecting trainees from both sectors. (Contains 1 table and 1 note.)