Research about the impact of the CEO's personality on firm-level outcomes has been ambiguous, partly because the underlying mechanisms remain largely unexplored. Given that the individuals most strongly influenced by a firm's CEO are the top management team (TMT) members, this study focuses on the CEO-TMT interface as a salient intervening relationship. We hypothesize that CEO personality traits of extraversion and openness to experience would influence firm performance indirectly through TMT behavioral integration (TMT teamness). Using multisource survey data from 138 small- to medium-sized firms, we test and find general support for a mediation model in which the CEO's personality traits are positively related to TMT behavioral integration, which, in turn, enhances firm performance. Limitations and implications for future research are also discussed.