This is one of a series of reports on the National Longitudinal Study of Mathematical Abilities (NLSMA). This one discusses the attempts to determine which of many variables had significant predictive power for student achievement on various mathematical scales. (NLSMA Reports No. 4-7 and 9 provide background information on the variables and scales that are discussed.) A stepwise regression analysis with a three-stage elimination was used to identify the best predictors. In the first series of analyses, most of the significant predictors were mathematical scales. A second series was used to determine the best psychological predictors. Finally, the mathematical and psychological predictors are merged and the total results presented. For related documents, see ED 044 277 - ED 044 283, ED 044 310, ED 045 447, and SE 016 669 - SE 016 691. (LS)