Close to two million first-year undergraduates enroll in developmental education each year. According to recent national estimates, less than half of students who start in developmental education go on to complete gateway courses and less than one-third eventually earn a degree. However, more research is needed to better assess potential relationships between developmental courses and student outcomes. This study comprehensively analyzes the effects of enrolling in and completing developmental education on associate degree completion--a key student outcome in the 2-year sector. Data for this study came from the Education Longitudinal Study of 2002 and the accompanying Postsecondary Education Transcript Study. Propensity score analysis and doubly robust techniques were used to estimate more accurate causal effects, while accounting for the non-random assignment into the treatment conditions. Furthermore, this study introduces propensity score matching for multivalued treatment conditions or dose-response analysis to the study of developmental education in order to estimate the average causal effects of enrolling in various quantities of developmental education on associate degree completion. Overall, when two groups of statistically similar students were compared, developmental education generally improved the chances of earning an associate degree. The dose-response analysis revealed that the relationship between the number of developmental courses a student takes and associate degree completion is not strictly linear.