In this quasi-experimental design (QED) study, we examined the impacts of Catapult Learning's Wraparound Supplemental Educational Services program on Grades 6-8 student math and reading achievement in selected schools in a large parochial school district. The primary focus of this report was Wraparound Supplemental Educational Services' impact on NWEA MAP Growth math and reading scores, as well as associations between Wraparound Services Schools attendance metrics and achievement outcomes. The present study used a student-level QED design, with students from five Wraparound Services Schools identified as the treatment group. The matched comparison group consisted of students from non-Wraparound Services Schools that did not receive supplementary services. Students were matched at the individual level on the basis of prior achievement and demographic variables. The present study was situated in a large parochial student district. The analytic sample consisted of 385 Grades 6-8 students receiving Wraparound Services Schools services and 385 matched (non-Wraparound Services Schools) students. Data sources included NWEA Measures of Academic Progress (MAP) Growth math and reading scores, as well as Wraparound Services Schools attendance metrics. The main attendance metrics of interest were counts of total program sessions attended for each student, by subject. Impact analyses showed a significant positive impact of Wraparound Services Schools on middle school math achievement, with treatment students outperforming matched comparison students by nearly 4 points. Subgroup analyses of this sample showed additional positive impacts for Grade 7, Hispanic, female, and Title I students. No significant program impacts were evidenced for reading achievement, with a small directionally positive impact observed. Counts of total program sessions were generally not associated with math or reading achievement after controlling for prior achievement and demographic variables.