Collecting treatment integrity data is critical for (a) strengthening internal validity within a research study, (b) determining the impact of an intervention on student outcomes, and (c) assessing the need for implementation supports. Although researchers have noted the increased inclusion of treatment integrity data in published articles, there has been limited attention to how treatment integrity is assessed. The purpose of this study was to review how treatment integrity is typically assessed in single-case design performance feedback articles. Doctoral students in school psychology coded 58 performance feedback studies to determine how treatment integrity data are assessed in this literature, and common intervention characteristics linked to treatment integrity assessment. Findings indicate that, although data were collected most frequently via direct observation by a researcher targeting intervention adherence, intervention characteristics varied widely across studies. Implications of results are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).