The effectiveness of internationalization support services (ISSs), as knowledge providers, is an important topic in international business literature. However, studies on ISS effectiveness have neglected the role of managerial cognition. Adopting a configurational approach, we thus focus on the interplay between the types of knowledge provided by ISSs and the managers’ inherited knowledge to explain the perceived effectiveness of ISSs. Results demonstrate that the acquisition of network knowledge from ISSs is a necessary condition, but not sufficient, to perceive them as effective. They especially show that the need to acquire diversified knowledge through ISSs depends on whether managers have international work experience or country-specific experience.