This article examines the influence of personal background characteris
tics, family involvement, and ability grouping on school commitment, w
hich, in turn, affects the extent of students' participation in school
crime, school misconduct, and school nonattendance. Observational and
survey data from a sample of 754 middle school students in Grades 7 a
nd 8 support the hypothesis that decreasing levels of school commitmen
t are linked to increasing rates of school crime, school misconduct, a
nd school nonattendance. Personal background, family involvement, and
ability grouping help to explain the level of school commitment. Highe
r school commitment is associated with being female, White, in the eig
hth grade, and in high-ability mathematics classes. Youths with more e
ducated mothers and youths whose parents are highly involved in their
schooling are also more educationally committed. School commitment med
iates much of the effects of personal background, family involvement,
and ability grouping on the school delinquency measures. These finding
s can serve as a basis for early school-based delinquency prevention e
fforts.