Traditional professional development focuses on declarative and procedural knowledge. That is, participants usually learn what to do and how to do it rather than when to do it and why it is important. In McREL's leadership development program, they focus first on providing participants with an overview of research findings found in their publication, "School Leadership that Works" (Marzano, Waters, & McNulty, 2005). During the program, participants explore 21 responsibilities of highly effective school leaders and learn about the importance of shared leadership, creating purposeful communities, and managing what McREL calls "first-" and "second-order" changes. In addition, they learn 11 research-based influences on student achievement identified by McREL's research and reported in the ASCD publication, "What Works in Schools" (Marzano, 2003). But that alone is not enough to become a highly effective school principal. Using cases in conjunction with a thorough examination of the research is a simple but powerful method for helping current aspiring school leaders gain the deep levels of knowledge they need to develop true professional wisdom. By reflecting on problems of practice and interacting with fellow principals, professionals can make sense of the consequences of decisions faced by the decision maker in a particular case. By examining the judgements the leader in the case made and reflecting on the results of those decisions, professionals, over time, can develop better judgement. By studying several cases, school leaders shorten their experience curve, compressing the experiences of others into a shorter span of time with the added benefit of not actually suffering the consequences of the mistakes made by the leaders in the cases. A sample case is appended. (Contains 1 exhibit.)