Background/Context: Increasing evidence suggests a connection between racial differences in rates of exclusionary discipline (suspensions/expulsions) and academic achievement by (Losen & Martinez, 2020; Reardon et al., 2018). Black students receive out-of-school suspensions and expulsions at disproportionately higher rates, which is associated with having lower test scores than White students (e.g., Noltemeyer et al., 2015). Although some research found positive associations between racial discipline gaps and achievement gaps (e.g., Pearman et al., 2019), there are two limitations of the current literature. First, many states and districts have implemented recent reforms to reduce exclusionary discipline (e.g., Hashim et al., 2018). However, there has not been a large-scale study on discipline and achievement gaps using recent data. Second, little is known about how differential discipline rates relate to differential academic "trajectories," which have a much weaker relationship with socioeconomic factors and can be used to better understand school contributions to student learning than static achievement at the school level (Houston & Henig, 2021; Reardon, 2019). Purpose/Objective/Research Question: The current study addresses these important gaps in the research by providing more recent evidence on the relation between racial disparities in discipline and in achievement, with particular focus on gains in schools across the nation. We ask: (1) Do schools with larger Black-White discipline gaps also have larger achievement gaps? (2) How are school discipline gaps associated with disparities in math and reading learning rates? We look at whether there is an association between differential exclusionary discipline and how achievement gaps develop during the school year. By estimating associations between the racial/ethnic gaps in discipline rates and within-year achievement gains, our goal is not to establish the causal impact of disciplinary action, but to further understand the relation between exclusionary discipline and student academic progress, which is currently very limited. Such findings could inform the theory underlying quasi-experimental studies of this topic. In light of the challenges in disentangling the causal direction between discipline achievement, there are unique advantages to examining academic gains. While generally low achievement may lead to a higher probability of receiving exclusionary discipline due to students' disruptive behavior or staff bias, it is unlikely that low academic gains would cause similar disciplinary action. In most schools, data on students' academic gains are not prominently featured and are unlikely to become the basis on which students are labeled or stigmatized. The probability of students' being suspended because of slow academic progress is extremely low; on the other hand, making slow progress during the academic year due to exclusion from instruction is highly probable. Nevertheless, this study is designed to provide descriptive evidence on the relation between the racial/ethnic disparities in discipline and within-year academic gains without speaking to the causal direction between the two. Population/Participants/Subjects: We link school-level discipline data in 2017-18 from the Civil Rights Data Collection to student-level assessment data from NWEA and school characteristics from the Stanford Education Data Archive. Leveraging assessment data in the fall, winter, and spring for 1,308,004 students in grades 6 to 8 in 6,841 schools, this is the first study to estimate the association between exclusionary discipline and within-year academic gains. Compared to the population of all NCES public schools serving grades 6 to 8, schools in our sample serve a lower percentage of students receiving free or reduced-price lunch (%FRPL, 52% vs 57%) and a lower percentage of Hispanic students (19% vs 25%) but a higher percentage of White students (64% vs 56%). Further, sample schools have slightly higher mean enrollment (489 vs 483) and Black student discipline rates (11% vs 10% out of school suspension and 0.53 vs 0.49 days suspended). The distribution of sample and population schools among city, town, suburb, and rural locales is similar, as are rates for White student discipline. Analysis: We use a 3-level growth model to model trajectories within the school year to understand whether Black-White gaps in learning rates are higher in schools with larger discipline gaps (see PDF for equations). At level 1, the test score for student "i" in school "j" at timepoint "t" (t=0 for fall; t=1 for winter; t=2 for spring) is modeled as a linear function of the months that a student has been in school. At the student level (level-2), an indicator for whether the student is Black is included to model gaps in both test scores at the end of the spring and learning rates across the school year. At level 3 (school), our baseline model (Model 1) only includes random intercepts and random slopes. In three conditional models, we add a set of school characteristics. Model 2 includes the Black-White gap in out-of-school suspension rates. Model 3 adds the out-of-school suspension rate for White students. Model 4, shown below, additionally includes the percent of students eligible for FRPL and the percentage of White enrollment, both grand-mean centered. The key parameters are the association between student-level gaps in learning rates and school-level discipline disparities. We run these models separately for each grade level and subject. All estimation is done using HLM 8 (Raudenbush et al., 2019). Findings/Results: We report two main findings. First, Black-White suspension gaps and achievement gaps persist (correlation= 0.15 for math, 0.19 for reading) in the vast majority of schools in 2017-18 despite the announcement of many reforms in school discipline practices. Second, Black-White disparities in exclusionary discipline rates are associated with lower learning rates during the school year for Black students in math but there is no association for reading. These findings point to discipline disparity as a key factor contributing to the expansion of Black-White achievement gaps during the school year reported in the extant literature.