This causal-comparative study examined the effect of revised placement rules on throughput student success for transfer-level mathematics students in California community colleges. This study was timely and relevant in providing insight into the educational reforms instituted by the AB705 legislature in California community colleges to maximize throughput success rates. Descriptive statistics were used to compare the observed throughput success rates from the academic year 2019-20 to the State's predicted success rates. Disaggregated data was obtained for student demographics and special status. The study used a quantitative research design with one hundred randomly selected transfer-level math students from each of the three revised placement levels. Kruskal-Wallis test and two proportion z-tests were performed to analyze significant difference in the dependent variable (throughput success rate) by the three independent variable groups (placement levels 1, 2, and 3). The tests revealed a statistically significant difference in the throughput success rates by placement levels. This was verified by chi square and post hoc tests. The data obtained from Spring 2020 was impacted by multiple confounding variables due to the COVID-19 pandemic. However, the comparison of results by terms, pathways, and disaggregation showed that the observed throughput success rates did not meet the State's threshold standard and that the placement levels did have a significantly lower impact on throughput student success. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]