Considerable disagreement exists on the merits of CEO-Chair duality. In recent years, there has been growing regulatory and investor pressure to split the titles of CEO and Chairman of the Board. In fact, there is a significant trend towards separation of the two titles. However, the empirical evidence in the literature is inconclusive on the impact of separating these roles. We argue that the inconclusive evidence arises from endogenous self-selection that complicates empirical identification strategies and the ability to recognize the correct counterfactual firms.