The data entry quality control procedures in discrete data entry tasks in the National Longitudinal Study (NLS) Fourth Follow-Up Survey are examined. Direct data entry terminals were used to key survey questionnaire item responses, telephone interview corrections, respondent background information and supplemental questionnaire responses into computer disk storage. Data entry error rates were computed on the survey questionnaires by selecting a random sample from each batch after initial keying of the data, rekeying the selected questionnaires by two additional operators and determing error rates on the basis of three keyings. In the implementation described, the overall error rate tolerance established for the NLS survey was not exceeded. The variable error rate over samples and operators on the selected supplemental questionnaires was 0.00040; estimated character error rate was 0.00023. The telephone interview additions and corrections, and directory information entry procedures are described. (CM)