This chapter explores the role of the Internet in health behavior placing particular emphasis on the issue of trust and trusting behaviors as this is seen as key to determining the impact of the Internet on health outcomes and behaviors. It examines the context of trust in relation to online health advice and information and presents a staged model of trust that helps reconcile differences in the literature. The chapter also presents a timeline approach to the study of trust and engagement in online health. It details the way in which health consumers are initially drawn to online resources through to their longer-term engagement and their influence upon health-based decision making. The chapter draws together the literature and the results of the work to present some conclusions and considerations for future research.