In this paper, event study methods are reviewed and summarized. The paper begins with discussion of one possible procedure for conducting an event study in section 2 ,section 3 sets up a sample event study which will be used to illustrate the methodology. Central to an event study is the measurement of an abnormal stock return. Section 4 detials the first step measuring the normal performance and, Section 5 follows with the necessary tools for calculating an abnormal return, making statistical inferences about these return, and aggregating over many event observations. The null hypothesis that the event has no impact on the distribution of returns is maintained in Section4 and 5. Section 6 discusses modifying this null hypothesis to focus only on the mean of the return distribution. Section 7 presents analysis of the power of an event study. Section 8 presents nonparametric approaches to event studies which eliminate the need for parametric structure. In some cases theory provides hypotheses concerning the relation between the magnitude of the event abnormal return and firm characteristics. Section 9 presents a cross-sectional regression approach that is useful to investigate such hypotheses. Section 10 considers some further issues relating event study design and the paper closes with the concluding discussion in Section 11.