A new ninth grade algebra course developed by the School Mathematics Study Group (SMSG) was evaluated: (1) what skills and abilities were developed to a greater extent in the new curriculum versus the traditional algebra curriculum; and (2) how achievement in each course was related to academic aptitude. Of teachers who volunteered to teach the SMSG curriculum, some were randomly assigned to teach SMSG courses and others to teach using a traditional curriculum. At the beginning of the school year, an academic aptitude test was administered to all participants. At the end of the year, all classes took both traditional and SMSG achievement tests. Results were based on item analysis of the two achievement tests, and the relation between the academic aptitude test and the achievement tests. The traditional classes scored higher on the traditional test and the SMSG group scored higher on the SMSG test. The SMSG students performed better on both familiar and novel items. On the traditional test, the traditional students did better on the manipulation items. The students, in general, learned what they were taught. Results also indicated that high aptitude students taught traditional algebra did relatively well on only the traditional test. High aptitude classes taught SMSG algebra did well on both types of tests, while low aptitude classes did poorly on both tests. Paper presented at the American Psychological Association Annual Convention, September 1, 1962.