In recent years the issue of women in corporate boards has gained extensive interest in practice as well as in the corporate governance literature. This paper adds to the existing debate focusing on the critical mass view in the investigation of women directors' contribution on board tasks. Previous studies debated that women's contribution on corporate boards would be better valued as their number increases; this study identifies that number in three or more women directors (critical mass). Basing on a sample of 213 Egyptian firms, we test hypotheses which relate to the critical mass of women directors (three or more women) to the board's strategic task, control task and service task. The results suggest that the critical mass (three or more women directors) is positively related to the board strategic task and negatively to the board service task, thus confirming that the critical mass view may contribute to a better understanding of board dynamics.