This report is the methodology report for the National Longitudinal Study of the High School Class of 1972 follow-up in 1986. The fifth follow-up survey of the National Longitudinal Study of the High School Class of 1972 (NLS-72) took place during spring and summer of 1986. A mail questionnaire was sent to a subsample of 14,489 members of the original sample of 22,652. A total of 12,841 persons returned the questionnaire, for a response rate of 89 percent. By the time of the survey, the sample members averaged 32 years of age and had been out of high school for 14 years. The fifth follow-up marked the first time that NORC conducted the NLS-72 survey. This report: (1) summarizes the base year sample selection procedures, and describes in detail the selection procedures for the fifth follow-up survey; (2) describes the calculation of sample case weights that adjust for differential probabilities of selection and for nonresponse within weighting cells; (3) examines the possible impact of survey nonresponse, a potential source of bias; (4) presents a description of nonresponse rates among various subclasses of the fifth follow-up sample; (5) describes procedures for computing sampling errors and design effects; and (6) discusses the approach NORC has taken to this problem. Sampling errors and design effects are presented for a set of proportions for the entire sample and for important domains or subgroups. Several "rules of thumb" are offered for estimating standard errors under various circumstances. The following are appended: (1) Weights and Nonresponse Adjustments; and (2) Design Effects and Sampling Errors.