This is the third in a series of reports concerning data collection activities on the National Longitudinal Study of the High School Class of 1972. Data collection activities included: (1) mailing a newsletter and address verification or correction postcard, followed by questionnaire packets, including a $3.00 incentive payment, and followup mailings; (2) telephone tracing of sample members whose newsletters were returned as undeliverable; and (3) conducting field interviews of nonrespondents to the mail survey. Data processing of the information included receipt control, pre-machine editing and coding, data reduction, error resolution, and microfilming. Changes in procedures for the fourth follow-up are recommended and the questionnaires and follow-up materials are appended. (MH)