The purpose of this research paper is to determine if a student's ACT math score is a significant variable in predicting grades in first year mathematics and engineering courses as well as determine if it is the only variable that plays a significant role in an engineering student's grades. Other variables were selected for consideration based on extant literature, with emphasis on prior knowledge, including high school rank, GPA, and ACT component scores as well as demographic variables. Using linear regression with forward selection, this work found that at Louisiana Tech University, a student's ACT math score is significant in terms of grade in both Pre-Calculus (the first math class an "on track" engineering student will take) and Engineering Problem Solving I (the first engineering class a freshmen student will take). However, high school GPA was a better predictor in both cases. Of the variables commonly available in student records systems, we conclude that both ACT math score and high school GPA should be considered when predicting performance in Pre-Calculus and Engineering Problem Solving, as each adds considerable explanation of variance.