Ventures of manufacturing multinationals into overseas markets are on the rise despite the recent rising protectionism. The optimal selection of international human resources is one of the critical success factors contributing to cross-border task performance and manufacturing efficiency. This paper addresses the expatriate selection problem by presenting an integrated two-stage optimization approach that makes use of data envelopment analysis and decision trees. A survey of 317 expatriates is conducted in multinational manufacturing productions for demonstrating the applicability and effectiveness of the proposed optimization approach. Findings reveal the optimal match between different sets of human critical success factors and the external system variables under two different settings of cultural flows. This study contributes to the existing research by proposing an effective and practical optimization approach for selecting the best expatriates for cross-border production assignments.