Completion of a first-semester chemistry (Chem I) course lays the foundation for understanding second-semester chemistry (Chem II) topics. The purpose of this study is to evaluate the influence of basic arithmetic skills on students' Chem II success in understanding mathematics-grounded concepts (e.g., solutions and aqueous reactions, kinetics, equilibrium, acids and bases, solubility and equilibria, thermodynamics, electrochemistry, and nuclear chemistry). Previous studies suggest a strong correlation between arithmetic preparation and performance in general chemistry courses, though few have focused on the second-semester course. In this investigation, researchers from six higher-education institutions in Texas, USA of different sizes and with student bodies of different diversities have collaborated to determine whether the Math-Up Skills Test (MUST) is able to reliably identify at-risk students from a population of n = 1599 at the beginning of a Chem II course.