Community colleges experience difficulties in effectively placing students in the first college-level, gateway mathematics course. The use of one standardized exam, such as the Texas Success Initiative Assessment (TSIA) has been proven ineffective. The effectiveness of using multiple measures is not known. This quantitative predictive correlational study examined if, and to what extent, the TSIA math score and cumulative high school grade point average (GPA) together predicted student success (numeric end-of-course grades) more effectively than either alone for community college students enrolled in a gateway mathematics course in the northeast region of Texas. The point-to-point theory provided the theoretical framework. The research questions evaluated to what extent the TSIA math score alone, the cumulative high school GPA alone, and the TSIA math score and cumulative high school GPA combined predicted student success in a gateway mathematics course more effectively than either individually. De-identified archival data, including demographics, the TSIA math score, GPA, and numeric end-of-course grades in the gateway mathematics course was provided by the site institution. The sample was 98 community college students in northeast Texas who had completed the gateway mathematics course in the Fall 2019 semester. The TSIA math score did not significantly predict student success in the gateway mathematics course. GPA significantly predicted student success, accounting for 8.1% of the variance. Findings indicated that only cumulative high school GPA should be used to place students instead of solely utilizing the TSIA for placement, and that other predictors of placements should be investigated. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]