The intended contribution of this paper is three-fold: first, to address recent calls for increasing construct validity in upper echelons research (Carpenter & Reilly,2006); second, to contribute to the discussions in the international management field about the relevant dimensions of firm internationalization; and finally, to address issues of causality between top management team internationalization and firm internationalization. The paper proceeds as follows. First, the theoretical basis for the development of the top management team internationalization construct is presented. Second, the relationships between TMT internationalization, firm internationalization and corporate performance are hypothesized. Third, the sample selection and the data