States have introduced a range of policies and strategies aimed at boosting college readiness by strengthening collaborations between secondary and postsecondary education sectors. One popular strategy is Early College High Schools, which allows historically underserved student groups to complete college-level coursework and improve their college readiness while still in high school. This study examined the influence of academic momentum during high school on key measures of postsecondary success for ECHS students in a suburban school district in Texas. This quantitative study analyzed data for five ECHS graduating classes from a Texas community college and school district. Data analysis for the first research question included descriptive statistics. The second research question used a multinomial logistic regression model to determine the relationship between momentum measures and postsecondary matriculation. At-risk and low SES students were less likely to matriculate to a 2- or 4-year postsecondary institution. Overall, ECHS graduates who earned a degree while still in high school were more likely to matriculate to a 2- or 4-year postsecondary institution. Support structures embedded within the small learning environment of an ECHS can provide graduates an opportunity to learn behaviors important for college success. Recommended strategies for improving the ECHS model are provided.