The present quasi-naturalistic study used socio-cultural theory (Wertsch, 1998), picture theory (Mitchell, 1994) and the use of historical agency as a second-order concept (Lee & Ashby, 2000; Seixas & Morton, 2013) as a way of examining the historical thinking of high school seniors as they investigated second-wave feminism. Existing literature reflects the ways in which students understand historical agency (Barton, 1997; Winter, 2001; Peck, Poyntz, & Seixas, 2011), but has yet to examine its use as a conceptual tool to dissect controversial issues in history, such as feminism. The main research question was: in what ways do high school seniors employ historical agency as an analytical lens in examining second wave feminism? Supporting research questions included: (1) In what ways do high school seniors make sense of historical agency as a tool for taking informed action? (2) How do high school seniors use historical context to evaluate individual, collective or institutional choices and their consequences? (3) How do high school seniors define gender and feminism in the context of examining the struggle for women’s political, social and/or economic equality? Data included students’ responses to a questionnaire, notes and audio-recording transcripts from a historical thinking exercise that used historic photographs, and audio-recordings and transcripts of semi-structured interviews. Results indicated that participants understand the complexities surrounding historical agency including an actor’s choice and their challenges. Participants were also able to use historical agency as a conceptual tool to investigate gender, controversial issues, and change over time. Still, participants struggled with historical context and causation and relied heavily upon a narrative of progress. Further consideration of students’ use of historical agency might offer new insight into supporting a more inclusive history curriculum that highlights historical agency and women’s history in more authentic ways.