In this study we use a unique data set to examine factors related to international commitment of owner-managed firms. We draw on different streams of research such as the knowledge-based view, the stage theory of internationalization and the new venture theory of internationalization to study firms involvement in foreign markets. Our results suggest that knowledge-based resources embedded in the management team and the firms attitude towards innovation increase international commitment. Further, consistent with the stage theory of internationalization, we find that firms demonstrate a pattern of steadily increasing foreign commitment. However, this latter finding was obtained only after taking into account the firms optimism in terms of future growth. Optimism among start-ups therefore may obscure the relationship between firm development stage on the one hand and international commitment on the other.