The focus of this study was to examine the effect of teaching based on inquiry-based learning versus traditional learning on mathematics achievement scores of undergraduate students enrolled in a college algebra class in a university classified as a Predominantly Black Institution. A college algebra course was chosen in this study due to the critical role it plays as a gateway for college completion and due to the generally high failure rate in college algebra. This study used a quasi-experimental design, with pre- and post-test to determine the effect of the instructional pedagogy on mathematics academic achievement of students. Analysis of covariance results from 41 students revealed, when controlling for college algebra readiness pre-test scores, students in the inquiry-based learning section showed significantly higher mathematics achievement post-test scores than in the traditional lecture section.