The cohort method was used to compute graduation and dropout rates for 81,847 New York City public high school students who entered grade 9 in 1983-84 and were expected to graduate in June, 1987. Separate studies were conducted for the following: (1) self-contained special education classes whose students were born in 1969 (Special Education Class of 1987); (2) a one-year follow up of the Class of 1986; and (3) preliminary study of the Classes of 1988 and 1989. Findings include the following: (1) the four-year dropout rates for the Classes of 1986 (21.8%) and 1987 (22.4%) were similar, and were expected to rise with additional years in school; (2) most students dropped out in the ninth or tenth grade and most were at least one year overage for their grade; (3) the dropout rate for the Special Education Class of 1987 was 24.1 percent; (4) dropout rates for the Classes of 1988 and 1989 will not differ from those of the Classes of 1986 and 1987; (5) the four-year graduation rates for the Class of 1986 (41%) and 1987 (39.2%) were similar, and were expected to rise with additional years in school; (6) general education students were more likely to graduate than special education students; (7) the assumption that high school is a four-year process may no longer be valid for school management decisions and statistical calculations due to the large number of students who take more than four years to complete high school. Statistical data are presented on four graphs and 19 tables, and two appendices provide a definition of the cohorts (general education) and a school-level analysis--Class of 1987. (FMW)