Abstract : Although interlocking directorates are regularly associated with a negative connotation, empirical evidence is far away from offering convincing answers about the performance effects of directorship interlocks. The huge variety of contradicting results can be explained both by the use of different theoretical frameworks and different value creation measures. In order to shed more light on the question of the role of busy directors, we develop a two-pillar model explaining the potential contributions of directorship interlocks to shareholder value creation. Based on a synthetic view of corporate governance, the model uses two disciplinary (work overload of busy directors and incentive effects coming from the external labor market of corporate directors) as well as three cognitive intervention levers (provision of information and knowledge, provision of general and specific competences, combination and exploitation of those elements). Moderating and controlling variables are added. The appropriateness of the model is tested through a 5-year comparison (2001-2005) of director networks within the largest French and German companies. We first present, both for a bi-national sample and national sub-samples, the major characteristics of the identified interlocks. In the empirical part, we conduct a panel data analysis checking for the influence of busy directors on corporate performance. We use two performance measures: one ex ante, the other ex post. Empirical tests indicate that the performance effect of interlocks depend on the type of board seats accumulated. Moreover, statistical modeling confirms the existence of cognitive contributions of director networks and shows mostly positive effects on value creation. Also, markets seem to anticipate director effects - both negative and positive - in a stronger way than an ex post performance analysis shows.