A systematic analysis was conducted of measurement and reporting practices related to procedural fidelity in single-case research for the past 30 years. Previous reviews of fidelity primarily reported whether fidelity data were collected by authors; these reviews reported that collection was variable, but low across journals and over time. Results of this review indicate that fidelity data collection was variable across journals, but increasing over time. However, despite previous recommendations for doing so, authors of many studies failed to report when data were collected, for what behaviors, and for which participants. Recommendations include continued fidelity measurement, increased breadth of measurement, increased precision of measurement, and explicit reporting of fidelity data and measurement procedures by authors.