Understanding influence on and effects of retesting is important to the selection practitioner. This article examines retesting effects on a series of selection measures for mechanically related positions to extend research that has been conducted in more controlled environments. While validity was not significantly different on retesting, time between test attempts and score increase on Spatial Reasoning were positively related, indicating the possibility of learning effects. Lower score increases were found for highly g‐loaded measures, and individuals who showed an increase scored more highly on average on their first attempt. Men tended to increase their scores more than women. We close with a discussion of the practical implications of our findings and how to build on them with future research.