This study examines whether an international work assignment can contribute toward expatriates developing greater cognitive complexity, the core building block of a global mindset and a capability critical to being an effective cross-cultural operative. Using a pre-test–post-test longitudinal panel design, cognitive changes in a sample of Australian and New Zealand expatriates working in 18 different countries were measured. The findings show that, as a group, the expatriates’ levels of cognitive complexity increased significantly during the 12-month study period. The individuals who experienced the largest increase were those who interacted most frequently with host culture nationals.