This paper delved into host and guests’ social exchange influences on their social and economic welfare at the International Tagus Natural Park. In this developing touristic territory, a preliminary study was surveyed in-depth. Among Portuguese and Spanish bordering villages, interviews with hosts were conducted. Two focus groups were set up to analyse the host and guests’ reciprocal behaviour as well as social reciprocity in the context of a pilot participative programme. Eventually, 194 questionnaires collected among Spanish and Portuguese hosts through a structural equation modelling of causal relationships data were analysed. Theoretical and practical conclusions can be drawn from the study. Social exchange has driven hosts to focus on promoting social values, emotions, attitudes and social reciprocity to welcome guests as complementary income to raise their standard of living. Visitors provide supplemented incomes to impoverished hosts. However, the seasonal and unstable job opportunities guests create display negative effects among locals.
