High school exit exams are affecting a growing majority of high school students. Although exit testing polices were enacted with the goal of improving student achievement as well as postsecondary outcomes, they also have the potential for negative effects. To better understand the effects of exit testing policies, in this article the authors systematically review 46 unique studies that pertain to four domains of expected influence: student achievement, graduation, postsecondary outcomes, and school response. The evidence reviewed indicates that exit tests have produced few of the expected benefits and have been associated with costs for the most disadvantaged students. This review suggests policy modifications that may attenuate some of the negative effects. (Contains 1 figure, 4 tables and 1 note.)