Honors directors and deans know or presume that retention and graduation rates of honors students substantially exceed those of non-honors students. In our research, we have attempted to better determine what portion of this success is attributable to the academic and other benefits of honors programs as opposed to the background characteristics of the students. Among the former, we would point to innovative and small classes, more individual attention for honors students from faculty and staff, residential learning communities, thesis experiences, and extra-curricular opportunities, all of which might be expected to make the college experience more engaging for honors students and thereby contribute to their success. Among the background characteristics, the superior academic achievement and ability enjoyed by honors students is a primary factor that determines retention and graduation (Cosgrove; Shushok; Slavin et al.), and other influences such as gender, in-state or out-of state residency, and family educational background are linked to both academic success and honors program participation. To better estimate the unique contribution of an honors program to retention and graduation outcomes, we have applied propensity score analysis (Guo and Fraser) to separate the effects of honors students' academic achievement and other background characteristics from the consequences of program participation.