Development and validation of a biographical data ("biodata") instrument for selection into the Air Traffic Control Specialist occupation is described. Bootstrapping was used to estimate correlations between item responses to the Applicant Background Assessment (ABA; 142 items; n=266), Biographical Questionnaire (BQ; 145 items; n=482), and average supervisory job performance ratings. Scoring keys were developed for the most predictive 80, 100, and 120 items from the instruments. Reliabilities for the proposed scales ranged from .74 to .78. Criterion-related validities were .59, .62, and .63 for the 80-, 100-, and 120-item versions, respectively.