The science-technology-society agenda has evolved over time to meet emerging educational aims in the light of changes in society and the environment. There is increasing emphasis on students' decision-making on socio-scientific issues (SSIs) not only to highlight the intricate relationships between science, technology, society, and the environment, but also to allow students to incorporate multiple viewpoints into the development of critical reasoning and responsible citizenship. Most research emphases have been on the rationality of reasoning rather than on the internal psychological context that underpins reasoning. This paper explores how these various aspects of reasoning interact in decision-making on SSIs in health contexts through case studies of recent issues in this field. The case studies reveal the negotiation of multiple influences in addressing SSIs in health contexts and the potential interactions between the psychological processes of individuals, science, and sociocultural perspectives. A tentative model to address these interactions emerges from this explorative study and has implications for the use of health-related issues in promoting SSI education. (Contains 1 figure.)