Economic and social problems facing many developing countries jeopardize the effectiveness and very existence of their national parks and protected areas. Rural poverty exacerbates the need for access to natural resources in protected areas and increases public conflict with protected-area management. A prerequisite for the long-term sustainability of parks and protected areas is public involvement and support for the conservation of natural resources. Towards the above ends, the present study analyses local residents' attitudes, knowledge, and concept of values concerning conservation and the management of natural resources in Machalilla National Park, Ecuador. A survey was administered of 90 households in three villages located within the Park boundaries and two villages adjacent to the Park. Survey results indicated that local residents living either within or adjacent to Machalilla National Park hold a variety of negative attitudes towards the Park. Positive attitudes tended to increase with respondents' level of education (X(2) = 19.001, df = 2, p < 0.0001) and knowledge about conservation issues (X(2) = 26.616, df = 1, p < 0.0001). Younger residents (X(2) = 12.960, df = 2, p 0.002), respondents perceiving benefits from the Park (X(2) = 14.292, df = 2, p = 0.001), and respondents reporting good relations with the Park staff (X(2) = 5.514, df = 1, p = 0.019), were more positive towards the Park. Factors influencing public attitudes are compared with study results in other countries. Negative attitudes stemmed from (1) a lack of public participation in the Park's creation and a misunderstanding of the National Park concept, (2) perceived restrictions on resource-use outweighing perceived benefits from the Park, and (3) conflicts between local inhabitants and the Park staff. Attitudes towards Machalilla National Park do not differ markedly between people living within or adjacent to the Park (F = 1.04, p = 0.8741). The results indicate management policies that would be needed to improve incorporation of the human populations into long-term strategies for sustaining the Park. A multifaceted approach, incorporating community involvement, environmental education, the development of feasible economic alternatives, and long-term social as well as ecological monitoring, is needed to attain also the goal of conserving biological diversity. The survey provided meaningful information for administrative decision-making and will provide data for monitoring the efficacy of subsequent policies.