After briefly describing case-study methodology in general, a number of ways of classifying different types of case studies are identified and discussed, including positivistic, interpretive and critical inquiry orientations. Using this latter framework, different approaches to case-study research are examined regarding their different assumptions about how cases might inform or transform practice. The paper then focuses on what kinds of knowledge or understandings can be constructed, and in what ways, from cases by readers and participants. The author argues that different types of cases may help the reader generate different kinds of knowledge (e.g. propositional, experiential and practical), provided the case enables readers to make meaningful connections (e.g. analytically, experientially, practically, personally) and helps them explicate tacit understandings about educational practices, reframe existing understandings or offer new possibilities for understanding or action.