The present study investigated whether parents' own behaviors and beliefs or their interpretations of their children's behaviors relate more closely to children's own mathematics achievement beliefs. Age and sex differences in children's perceptions of their parents' beliefs were explored. A total of 740 children in fifth through twelfth grades completed a questionnaire assessing their achievement beliefs in mathematics (specifically, self-concept of math ability, perceived difficulty of math, importance and value of math, expectancies, and intentions to take more math). The questionnaire tapped children's beliefs about the degree to which their parents enjoyed and used math skills and children's perceptions of their parents' beliefs about themselves. Parents completed a questionnaire assessing their own beliefs about math, their backgrounds in math, their perceptions of their children's math abilities, the value and importance of math, and their expectancies for their child's math performance. Results indicated that parents' own achievement beliefs concerning mathematics and their backgrounds in math were not related to children's beliefs. However, parents' beliefs about their children were related to children's beliefs. Though parents may have contributed to girls' lower expectancies in math, they did not appear to influence directly either girls' or boys' intentions to take more math. Children seemed to have fewer sex-differentiated views concerning mathematics than their parents. (RH)