Information necessary for informed use by practitioners of higher-order thinking skills (HOTS) tests is presented. Assessment instruments that (1) have as a basic assumption that thinking skills can be taught; (2) provide information that can be useful for instructional planning related to complex thought processes; and (3) have content that is taught, provide information that can be useful for instructional planning related to complex thought processes, and have content that is related to skills needed to function with reason in the real world are discussed. Content, format, and purpose must be considered in test selection. Although most current tests are designed for Grades 4 and above, some are designed for grades as low as pre-Kindergarten. Most tests cover a broad grade span. Cognitive skills included in HOTS are discussed, assessment issues are reviewed, the current state-of-the-art in assessment is outlined, and steps in selecting a HOTS test are described. Appendix A contains individual reviews of 10 HOTS tests and brief descriptions of other critical thinking, problem solving, or decision making tests. Two developmental tests are reviewed; eight others are briefly described, as are specific tests of creativity, achievement, and ability. Local, state, and federal programs with testing resources are described in other appendices. Appendix D contains a checklist for selecting HOTS tests. Tests are further indexed by grade level and title. (SLD)