Focusing on parental networks--a central dimension of social capital--this article uses ethnographic data to examine social-class differences in the relations between families and schools. We detail the characteristics of networks across different classes and then explore the ways that networks come into play when parents are confronted by problematic school situations. The middle-class parents in our study tended to react collectively, in contrast to working-class and poor parents. The middle-class parents were also uniquely able to draw on contacts with professionals to mobilize the information, expertise, or authority needed to contest the judgments of school officials. We did not find substantial race differences. We affirm the importance of a resource-centered conception of social capital that grants the issue of inequality a predominant place. (Contains 7 tables and 18 notes.)