Museum settings including aquariums, zoos and science centers rely heavily on their volunteer docent populations to interact with and communicate science and conservation concepts to the visiting public. The interactions docents have with museum visitors are important to meeting the educational expectations of museums and improving public science literacy as a whole, yet research to date is limited around docent practice, docents' reflections on that practice nor the sources for docents to learn that practice. Thus, we have little understanding of the interpretive practice docents actually undertake whilst interacting with visitors, why they choose to enact particular strategies, and how they came to learn those practices. Using a grounded qualitative approach within a framework of mediated action and cultural historical activity theory, this case study utilized video observations of docent practice at a science center, pre and post observation interviews, and focus groups to 1) document docent practices for engaging visitors, 2) explain those practices from the docents' own perspectives, and 3) examine those practices from the point of view of how they align with teaching and learning theories and interpretive practice. Thematic analysis using constant comparative methods demonstrate four claims about docent practice: 1) docents view teaching in the museum as opportunities to spark interest with these new experiences. Practices are chosen to engage visitors in these experiences. Docents choose to highlight these experiences as they believe they are reasons to be engaged; 2) docents as teachers are perceptive about their audience. They pay attention to patterns and provide information in response to those patterns. Docents utilize a shared repertoire of practice and information in their community developed from understanding visitor patterns of interest; 3) docents care about their setting and the exhibits within it. They also care about the visitor experience as a whole, and have to be flexible when working with different types of learners. They believe that being a docent means balancing potentially conflicting roles; and 4) docents use interpretation as a pedagogy to engage visitors with science and create personally meaningful experiences. Analysis of significant interactions between docents and visitors shows that such practices are mediated through a variety of discursive and physical tools and implemented by docents as a means of engaging visitors with science and conservation. Moreover, most of these skills appear to be learned on-the-job within their communities of practice, and while specific docent actions and skills may be different across contexts, member checks with docents working in other museum settings demonstrate the resonance of the findings across contexts. The findings of the study are placed in the context of interpretation theories of communication as well as research on docents as lifelong, free-choice learners both facilitating and participating in societal STEM learning activity. Findings and methods of research from this study are valuable to the greater understanding of how docents learn and enact interpretive practice and the development of more effective professional development for docents in museum settings. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]