Drawing on data collected as part of a qualitative action research study, our analysis examines the reflective thinking skill of candidates as they begin a two-year principal preparation program. As leadership educators, we noticed that our highest performing students were also the most skilled at thinking reflectively. Using candidates' writing samples as a proxy for reflective thinking, we looked systematically at students' written work to assess their skill at engaging in reflective thinking. Using Valli's (1997) "Orientations to Reflective Thinking" as an analytic frame, we found that candidates varied in their readiness to engage in reflective thinking. We now use this framework with candidates to assess and guide their development as reflective practitioners. We believe that aspiring leaders need robust practical and conceptual tools for anticipating and solving the complex problems and challenges they will ultimately face. Given the difficulty that our students demonstrate when asked to reflect on their learning and development as leaders, reflective thinking can and should be one of those tools.