The authors used data from the Early Childhood Longitudinal Study-Kindergarten cohort to examine whether parents' knowledge of their children's reading and mathematics skills varies by academic domain and parents' income group or ethnicity. Of particular interest was how parents' knowledge is moderated by school- or home-based involvement. Parents' knowledge was moderately related to their children's reading and mathematics scores. However, there were systematic income-and ethnicity-related differences in the correlations. Poor parents were reportedly less involved at home and school than nonpoor parents. White, non-Hispanic parents were more involved at school than other parents. School-based rather than home-based involvement was related to the strength of the correlations between parents' knowledge and children's reading and mathematics scores.