There is extensive evidence suggesting that school suspension is correlated with poor academic performance. However, many studies examining the association between school suspension and achievement focus on the effects of out-of-school suspension specifically. While in-school suspension is offered as a less harmful alternative consequence to out-of-school suspension, the effects of in-school suspension on academic achievement are largely unknown. This article examines the association between in-school suspensions and academic failure on standardized achievement tests. The study utilized secondary data from two cohorts of 380,826 ninth-grade students enrolled in Texas public schools to investigate how many in-school suspensions result in failure on a state standardized achievement test. Our results show that a single in-school suspension is predictive of significant risk for academic failure (greater than 25% chance of failure) on a state-wide standardized test controlling for a host of individual and school characteristics. We also find that this relationship between discipline and risk for standardized test failure is more pronounced for students of color. The implications for school psychologists in terms of curtailing the potential negative impact of in-school suspension on student achievement are discussed.