The "Cognitive Tutor[R] Algebra I" curriculum, published by Carnegie Learning, is an approach that combines algebra textbooks with interactive software. The software is developed around an artificial intelligence model that identifies strengths and weaknesses in each individual student's mastery of mathematical concepts. It then customizes prompts to focus on areas where the student is struggling and sends the student to new problems that address those specific concepts. The What Works Clearinghouse (WWC) reviewed 14 studies on "Cognitive Tutor[R] Algebra I." One of these studies meets WWC evidence standards; the remaining 13 studies do not meet either WWC evidence standards or eligibility screens. Based on the one study, the WWC found potentially positive effects on math achievement. The conclusions presented in this report may change as new research emerges. Six appendices include: (1) Study characteristics; (2) Outcome measures; (3) Summary of study findings; (4) Summary of additional findings; (5) Rating by achievement domain and (6) Extent of evidence by domain. (Contains 8 footnotes.) [This report has been updated to include reviews of studies released since an earlier WWC Intervention Report. For the previous report, see ED499299.]