The purpose of this study is to assess the effectiveness of a mandatory online supplemental instruction program in an introductory cell and molecular biology course at a community college in Northern Nevada. To accomplish this, the study focused on the dependent variable of course GPA, and the issuance rate of "D" or "F" letter grades and withdraws for students who enrolled in sections which used mandatory online supplemental Instruction. The theoretical framework of Vincent Tinto's departure theory and Steve Astin's student involvement theory guided this quantitative study. To accommodate this study, sections of introductory cell and molecular biology were re-designed to fit mandatory supplemental instruction into the weekly schedule. Student course GPA differences were assessed using the non-parametric Mann-Whitney U test. Student demographics and environmental demographics, including mandatory supplemental instruction attendance, were assessed using a multiple linear regression model. A chi-square test of independence was used to identify any relationship between students who earned a D, F, or withdrew from the course, and their participation in mandatory supplemental instruction. Results indicate that students who enrolled in sections of introductory cell and molecular biology which incorporated mandatory supplemental instruction had significantly higher course GPA scores as compared to their counterparts. It was further identified that the number of sessions attended is directly proportional to a student's GPA. These findings were strongest in traditionally disadvantaged populations suggesting that mandatory supplemental instruction is an effective way to bring equitable education to our systems of higher education. [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.]