Out-of-level testing is an underused strategy for addressing the needs of students who score in the extremes, and when used wisely it could provide educators with a much more accurate picture of what students know. Out-of-level testing has been shown to be an effective assessment strategy with high-achieving students; however, out-of-level testing not been shown to work well with low-achieving students. Thus, the primary focus of this manuscript is on out-of-level testing with high-achieving students. A brief history of out-of-level testing is provided, followed by several guidelines for when out-of-level testing should be used. Finally, the authors offer examples on how to use out-of-level testing.