Social-capital explanations of school outcomes, particularly of the school outcomes of immigrant children and children of immigrants, have come into wide use in recent years. These explanations attempt to account for individual or group variations in school performance by viewing the family and community relations that surround children as forms of investments that yield payoffs in schools. These family and community relations are seen as specific to immigrant groups, or "ethnicity as social capital. The author believes that although this ethnicity-as-social-capital approach can be a valuable one, it runs the risk of overlooking the complex and contradictory nature of the association between immigrant social relations and the adaptation of immigrant children and children of immigrants. This article explores how a relatively high average level of achievement among Vietnamese American students has been maintained in recent years by cultural values that are conducive to achievement and by bounded social networks that maintain these values. The author and his colleague analyze the disadvantageous aspect of social capital as an investment of cultural values through social relations.