A report of 1 phase of a larger cross-cultural project, this paper is primarily concerned with the interrelated influences of perceived parental support and social class origins on the educational plans of comparable populations of American high school seniors and Norwegian "ungdomskole" students. The data was obtained via a questionnaire survey from 2,313 graduating seniors in the high schools serving 4 selected rural areas of Kentucky and West Virginia and from 1,396 students in the terminal classes of the comprehensive schools serving 3 selected rural areas of Norway. Parental interest, social class origin, and academic performance, it was concluded, have important independent and interrelated effects on educational mobility in both Norway and the United States. Cross-culturally, social class origin and academic performance are the more consistent determinants of educational mobility, and their effects tend to be more stable. The findings further demonstrated that among American high school boys and lower class boys in the Norwegian comprehensive schools, a superior performance record in high school functions as a family involvement catalyst among the lower classes. Lower class girls, however, are at a continual disadvantage compared with upper class girls, regardless of past academic performance. The implication, viewed from a comparative perspective, is that the specific societal context may provide useful insights into the relative importance of the social-structural determinants of educational mobility. (HBC)