This article studies the efficacy of ALEKS Preparation, Placement and Learning (PPL) in assessing the likelihood of a student succeeding in a first-semester calculus course. Proctored ALEKS PPL assessments were taken by all students enrolled in Calculus 1 during five semesters in which all students took a tightly coordinated course that included common exams. Bivariable logistic regression was used to assess the impact of ALEKS PPL and several other demographic predictor variables including gender and ethnicity. ALEKS PPL proved to be a very effective predictor for student passing Calculus 1 and also in achieving higher grade levels.