Early Colleges (ECs) provide high school students access to college coursework with the goal of increasing postsecondary opportunities for traditionally underrepresented students. We examine the impact of ECs on postsecondary attainment, calculate the resulting monetary benefits, and then estimate the per-student costs of ECs compared to traditional high schools to compare costs and benefits. Our findings indicate that students enrolling in ECs in our study are more likely to attend college and graduate with an associate or bachelor's degree. Increased educational attainment from EC enrollment results in lifetime benefits of almost $58,000 per student. ECs cost approximately $950 more than traditional high schools per student per year, resulting in an overall cost of $3,800 more per student across four years of high school. Comparing benefits to cost, we estimate a net present value (NPV) of $54,000 per student and a benefit to cost ratio of 15.1. Even when using conservative estimates of costs (upper bound) and benefits (lower bound), we calculate an NPV of over $27,000 and a benefit to cost ratio of 4.6. These results indicate that investment in ECs pays off through increased earnings for EC students, increased tax revenue, and decreased government spending. [This is the online version of an article published in "Education Finance and Policy." This article is based on the report "The Costs and Benefits of Early College High Schools" (ED606242).]