This study investigated the effects of general intelligence and seven specific cognitive abilities on college-age students' mathematics achievement. The present investigation went beyond previous research by employing structural equation modeling. It also represents the first study to examine the direct and indirect effects of general and specific cognitive abilities, simultaneously, on the mathematics achievement of college-age students. A model developed using the Cattell-Horn-Carroll theory of intelligence was the theoretical model used in all analyses. Data from 1,054 college-age students who participated in the standardization of the Woodcock-Johnson III (Woodcock, McGrew, & Mather, 2001) were divided into a calibration sample set and validation sample set. The calibration data set was used for model testing and modification and the independent validation sample data set was used for model validation. The specific areas of intelligence demonstrating direct effects on the mathematics achievement dependent variable were Crystallized Intelligence and Fluid Reasoning. The effects of general intelligence were found to be "indirect" in the college-age sample. Implications for instruction and intervention to improve college student's mathematics achievement are provided.