This paper explores the nature and relationship of the positions of CEO and chair of the board of directors through two related analyses, one examining CEO and board chair turnover and the other examining consolidations and separations in these two positions, using transition-rate analysis, in a sample of 671 large American manufacturing firms for the period from 1978 to 1980. Both turnover and structural change in the top positions were found to depend on firm performance and industry structure; turnover also depended on firm size and the structure of the positions, and structural change also depended on board structure, controlling for retirements. The results highlight the power of the CEO, the tendency to consolidate the top positions under the CEO, and the greater accountability of the person in the combined position for firm performance. The paper concludes with some implications of the findings for understanding the CEO and board chair positions, with an emphasis on top-management power, makes recommendations for research on turnover, and provides suggestions for corporate behavior, based on the results of this study.