The present meta-analysis sought to quantify the average degree of aggregated test score distortion due to rapid guessing (RG). Included studies group-administered a low-stakes cognitive assessment, identified RG via response times, and reported the rate of examinees engaging in RG, the percentage of RG responses observed, and/or the degree of score distortion in aggregated test scores due to RG. The final sample consisted of 25 studies and 39 independent samples comprised of 443,264 unique examinees. Results demonstrated that an average of 28.3% of examinees engaged in RG (21% were deemed to engage in RG on a nonnegligible number of items) and 6.89% of item responses were classified as rapid guesses. Across 100 effect sizes, RG was found to negatively distort aggregated test scores by an average of 0.13 standard deviations; however, this relationship was moderated by both test content area and filtering procedure.