Event studies have become one of the most important methodological approaches to empirical research in frnance and accounting. This paper discusses the nature of event studies, differentiating the four basic types: information content, market efficiency, model evaluation and metric explanation. A structure is identified for the conduct of event studies and the steps discussed. Specific studies in the literature are cited as illustrations of various points. Finally, a number of issues of interpretation, evaluation and design are discussed which are crucial to the effective conduct and understanding of an event study.