To identify the effects of the senior high school experience on the vocational development of youth, a 10-year longitudinal study was undertaken to trace the development of ninth graders from three Pennsylvania school districts. Included in the study are all Altoona students who finished Grade 9 in 1969, and all the Hayleton and Williamsport students who completed Grade 9 two years later. This first report describes the total 10-year study and provides a reference point for future publications resulting from the study. Implications for curriculum planning and guidance are discussed. Although primarily applicable to the three districts involved, the findings are generalizable to other school systems. A related document is available as VT 014 081. (BH)