A STEM (science, technology, engineering and mathematics) analysis project undertaken in the context of a historic visitor site is described. The project offered different types of opportunity for scientific working, and involved four distinct groups of participants. Two distinguishing features of the different groups of participants were their primary motivation for engagement with the activity, and their level of previous engagement with formal STEM education. Participants in different parts of the project were assessed as to their level of science capital (Archer, L., Dawson, E., DeWitt, J., Seakins, A., & Wong, B. (2015). "Science capital: A conceptual, methodological, and empirical argument for extending bourdieusian notions of capital beyond the arts." "Journal of Research in Science Teaching," 52, 922-948). Drawing upon engagement theory, the observable behaviours were used as an indicator of engagement and then categorised according to (Barriault, C., & Pearson, D. (2010). "Assessing exhibits for learning in science centres: A practical tool." "Visitor Studies," 13(1), 90-106) taxonomy. The analysis showed that learner engagement was exhibited at different levels by the different categories of participants, with higher levels of engagement exhibited by participants with a higher level of science capital. Although there was general correlation between the level of science capital and the proportion of higher engagement learning behaviours, one group of participants deviated from this trend. The findings indicate that the level of science capital is a key determinant of engagement and associated learning behaviours, but did not completely account for participants' engagement in the science outreach activity.