The cohort method was used to compute graduation and dropout rates for 82,935 New York City public high school students who entered grade 9 in 1984 and were expected to graduate in June 1988. Separate studies were conducted for the following: (1) a 1-year follow-up of the Class of 1987; (2) a 2-year follow-up of the Class of 1986; (3) a preliminary study of the Classes of 1989 and 1990; (4) self-contained special education classes whose students were born in 1970 (Special Education Class of 1988); (5) a 1-year follow-up of the Special Education Class of 1987; (6) a 2-year follow-up of the Special Education Class of 1986; (7) and a preliminary study of the Special Education Classes of 1989 and 1990. Findings include the following: (1) the 4-year dropout rates for the Classes of 1986 (21.8 percent), 1987 (22.4), and 1988 (20.8) 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 1 year overage for their grade; (2) dropout rates for the classes of 1989 and 1990 will not differ from those of the Classes of 1986, 1987, and 1988; (4) the 4-year graduation rate for the Class of 1986, (41.0 percent), 1987 (39.2 percent), and 1988 (40.1 percent) were similar, and were expected to rise with additional years in school; (5) the dropout rate of the Special Education Class of 1987 had risen to from 24.1 to 31.3 percent; (6) the dropout rate of the Special Education Class of 1986 had risen from 24.5 to 37.5 percent; and (7) the assumption that high school is a 4-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 4 years to complete high school. Statistical data are presented on three figures and 27 tables. Three appendices provide a definition of the cohorts (general education), a school-level analysis for the Class of 1988, and graduation and dropout rates for the Class of 1986. (PJ)