In addition to the influences of individuals' prior academic experiences, individuals' behavior outside of school can also affect their academic self-concepts. Specifically, a national study of high school sophomores (the High School and Beyond study) who remained within the same school for both their sophomore and senior years found that the greater the number of hours of employment students reported performing during their sophomore, junior, and senior years of high school, the lower their global academic self-concept (Marsh, 1991a). This relationship was found even controlling for the fact that those who work many hours are likely to differ from those who do not in a number of ways, such as in their prior academic skills, their academic track, the time they spend on homework, their school absences, their family background, and even their prior levels of academic self-concept.