The effectiveness of the current selection system used to hire eligibility technicians was studied, and the predictive relationship between existing selection instruments and job performance criteria was investigated. Eligibility technicians are employees of San Diego County (California) whose duties include determining the eligibility of applicants for social services. The current selection system consists of a multiple-choice examination and a composite assessment including a training and experience application blank and an interview. Job performance criteria were subjective (supervisory ratings and factor scores) and objective (job tenure and turnover). Scores on the subjective criteria were taken at three points in time: mid-probation, final probation, and first annual performance review. Information was gathered for all applicants for the position of eligibility technician between 1986 and 1990 (449 employees at mid-probation, 409 at final probation, and 250 at the first annual performance review). Applicants included Blacks, Hispanic Americans, Asian Americans, American Indians, Whites, and Filipinos. The written test was a valid predictor of job performance, with a positive relationship between the test and supervisory ratings at all times. The application and interview did not predict job performance. The written test had an inverse relationship with tenure and was significantly correlated with turnover. The written test was a fair and unbiased estimate of job performance that did not discriminate against applicant classes protected by the county. Suggestions for improvement of the selection process are given. Thirty-six tables and a list of 101 references are included. (SLD)