The COVID-19 pandemic disrupted educational systems, leading to significant learning loss and credit deficiencies among high school students, particularly in California's comprehensive high schools. This research addressed these challenges by exploring innovative strategies through a social-ecological model and ecological systems theory to improve retention rates and on-time graduation. Using a qualitative-dominant mixed-methods approach, the study included interviews with education partners from an online charter school, representing diverse demographics. Findings revealed the pandemic's impact on credit deficiency and identified effective programs and strategies to support credit-deficient students, improving their chances of graduating on time. The project focused on providing holistic support within comprehensive high schools to help students overcome learning gaps and recover credits. It underscored the necessity of keeping students enrolled and supporting their on-time graduation, directly addressing the pandemic's adverse impact on academic progress. By proposing innovative solutions and extensive support within comprehensive high schools, this study aimed to mitigate the pandemic's impact on students, promote graduation rates, reduce dropout rates, and enhance post-secondary readiness. The research emphasized the importance of continuous innovation in education to ensure equitable access to high-quality education for all students, highlighting the project's role in fostering stability in the educational system amidst unprecedented global challenges. [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.]