This thesis consists of five papers dealing with fairly heterogeneous issues, based on the problems or topics analyzed, but also based on the methodologies used to approach them. The overriding motives are the design of environmental policies in the context of a typical developing country (where Costa Rica is used as a representative of such countries), and the study and application of techniques that can provide the necessary information for policy-making.

The private demand for a hypothetical vaccine that would provide lifetime protection against HIV/AIDS to an uninfected adult was measured in Guadalajara, Mexico, using the concept of willingness to pay (WTP). A 91-question survey instrument was administered by trained enumerators employing contingent valuation techniques to 234 adults, aged 18-60.

We examine households' demand for improved water services in Kathmandu, Nepal, where the government is considering the possibility of involving the private sector in the operation of municipal water supply services. We surveyed a randomly selected sample of 1500 households in the Kathmandu Valley and asked respondents questions in in-person interviews about how they would vote if given the choice between their existing water supply situation and an improved water service provided by a private operator.

It is argued that there has been little attention given to comparing the range of 'participatory' research methodologies available to determine which among them afford donor agencies cost-effective means of obtaining accurate information about the views and preferences of project stakeholders. The paper contributes experimental evidence to this debate by comparing two research methods: community meetings and household surveys.