In this article we chronicle a particular professional development initiative designed to promote the acquisition of an evaluation habit of mind within an educational context. After describing the rationale behind this initiative in some detail, we proceed to map the experiences of four of the participants--a principal, a vice principal, a consultant, and a teacher--as they journeyed toward an understanding of evidence-informed decision making. A combination of document analyses and exit interviews allowed us to plot the developmental course by which this evaluation mindset unfolds. Ultimately, the process of using data as evidence for decision making is revealed as one of developing intrinsic motivation by way of personal "meaning making." The three overarching cognitive themes of preconceptions, frameworks, and reflections given in the National Research Council's synthesized report on how people learn (Donovan, Bransford, & Pellegrino, 2000) are taken as the structural guideposts for the necessary construction of meaning.