Statistics is an important subject in psychology and social science education. However, inadequate mathematical skills can pose a barrier to learning statistics. Some educators have suggested that students' math skills are declining. The present research examined trends in the math skills of psychology undergraduates across 21 years. Students (n = 3735) who were enrolled in an introductory psychology statistics course from 1990 to 2011 completed a pencil-and-paper math skills test. Over the 21-year period, there was a 9% decline in math skills scores and a 28% increase in the number of attempts required to pass the test. Consistent with national trends, SAT Math scores also increased by 7%; however, the pencil-and-paper math skills test was nearly twice as predictive of course performance as was the SAT. Results suggest that important math abilities have declined. Implications for statistical education in the social sciences are discussed.