The Substance Education Program of the Iowa Department of Education began a series of tri-annual studies of youth substance behaviors, attitudes, and knowledge in the fall of 1975. The youth studies have continued with data collections in 1978, 1982, 1984, and 1987. A survey administered in 1987 to Iowa students in grades 6, 8, 10, and 12 focused on substance use, parent modeling behaviors, parent normative standards, peer modeling behaviors, school normative standards, perceived school influence, and intervening variables related to adolescent preferences and norms. The findings of the 1987-88 Iowa Study of Alcohol and Drug Attitudes and Behaviors among Youth will be presented in three reports focusing on: (1) normative data for 1987 and relevant comparisons with previous studies; (2) individual district reports of student responses to selected survey items; and (3) normative data packets for the four size categories of districts. This report presents normative data for the 1987 survey and comparisons with prior studies. An introduction is followed by a description of study procedures and sections on findings for self-reported substance use and norms, external influences, and personal variables. A summary and recommendations section presents findings relevant to four research questions dealing with the present status of substance use, attitudes, and knowledge; important trends in these areas; the major influences in a youth's decision to use substances; and actions suggested by the findings for school persons. Sixty-four data tables are included. (NB)