In 2019, the Rhode Island Department of Education (RIDE), in partnership with the University of Rhode Island (URI), launched the Work-Based Learning for Computer Science (WBL4CS) project through an Education Innovation Research (EIR) grant. The initiative aimed to expand access to computer science (CS) education for high school students, particularly those from underrepresented groups (URGs), by implementing a two-year CS pathway that included an industry-mentored work-based learning (WBL) course. A quasi-experimental design was used to evaluate the program's impact in 20 Rhode Island high schools, with 10 schools receiving the intervention and 10 serving as matched comparisons. The study assessed multiple student outcomes, including Advanced Placement CS Principles (AP CSP) course completion, CS proficiency, course grades, engagement, interest in CS, and career intentions. Results showed a statistically significant positive effect of the WBL course on CS proficiency and student-reported engagement. However, there were no statistically significant effects on AP CSP course completion, course grades, attendance, interest in CS, or career intentions. The program was implemented with high fidelity in Years 2 and 3, although the COVID-19 pandemic presented challenges in Year 1 and may have influenced outcomes. Overall, findings suggest that integrating WBL into CS pathways can positively impact student proficiency and engagement, but additional support and extended exposure may be necessary to influence broader academic and career outcomes. The study highlights the importance of equitable access to authentic learning experiences in CS education and the need for continued investment in scalable models that support diverse learners.