The construct validity of the Occupational Aptitude Patterns Map (OAP Map), an occupational classification system based on ability requirements, was investigated by placing the positions held by a large, nationally representative sample of full-time employed, young, civilian adults into the classification system. The patterns of characteristics exhibited by these young adults were examined to determine whether the patterns coincided with those predicted by a relevant theory of job aptitude requirements. The results largely supported the structure of the OAP Map. The results indicated that the OAP Map captures differences across jobs in their requirements for general cognitive ability, although the overlap across job clusters is large. The OAP Map differentiates jobs also on the basis of their requirements for specific abilities (e.g., scientific/mechanical ability), once the effects for general cognitive ability requirements are taken into account.