The General Aptitude Test Battery (GATB), a 12‐test battery purporting to measure nine occupation‐related aptitudes, is one of the most widely used test batteries in the field of job selection. Despite its widespread use, however, little research has been carried out to investigate its factorial assumptions. The present study looks at the factorial structure of the GATB based on a large Irish sample. The results indicate that the GATB does not adequately measure nine specific underlying aptitudes, but four, more general, higher order aptitu