This paper examines how disadvantage affects educational outcomes, in this instance, Year 12 completion. While previous studies have found a strong link between parental education or occupational status and Year 12 completion, this research was able to capture a broader set of cultural, material and resource aspects of disadvantage. It did this by undertaking a comparative analysis of two datasets--the Longitudinal Surveys of Australian Youth (LSAY), which collects the more familiar information about parental education and occupational status, and the Youth in Focus (YIF) survey, which provides an additional set of disadvantage measures, including family income and welfare receipt history, as well as information about the respondent's earlier educational experiences and risky behaviour. This paper reveals that: (1) Cultural factors, including poor school experiences, participation in risky activities such as smoking and alcohol consumption, and aspirations are the main predictors of Year 12 completion; (2) Material factors, as measured through current family income, have only a small effect on Year 12 completion; and (3) The role of the commonly used indicators of disadvantage associated with school completion, including parental education and occupational status, is shown to be less significant than previously indicated. This report shows the importance of getting behind simple measures of family background in understanding the relationship between disadvantage and educational outcomes. (Contains 11 tables and 12 footnotes.) [For Data Appendix, "School Completion: Data Appendix. Support Document," see ED533336.]