There is a well established socioeconomic gradient in educational attainment in all countries: young people from a low socioeconomic status (SES) will, on average, receive less education and do less well at school. While this is true virtually everywhere, this SES gradient is noticeably higher in Ireland compared to other OECD countries despite much effort in recent decades to address this inequality. This study evaluates a university access program in Ireland that provides financial, academic and social support to low SES students both prior to and after entry to university. It uses a natural experiment involving the gradual roll-out of the program to identify the effect of the program. The program has parallels with US Affirmative Action programs, although preferential treatment in this case is based on SES rather than ethnicity. Evaluating the effectiveness of programs targeting disadvantaged students in Ireland is particularly salient given the high rate of return to education and the lack of intergenerational mobility in educational attainment. Overall, we find positive treatment effects on first year exam performance, progression to second year and final year graduation rates, with the impact often stronger for higher ability students. We find similar patterns of results for students that entered through the regular system and the 'affirmative action' group i.e. the students that entering with lower high school grades. The program affects both male and female students, albeit in different ways. The study is unable to identify which specific component of the treatment is responsible for the effects but we find no evidence that changes in the financial support have an effect on student outcomes. This study suggests that access programs can be an effective means of improving academic outcomes for socio-economically disadvantaged students.