Research summary Studies of how divestitures affect firm performance offer mixed results. This paper unpacks relationships between divestitures and subsequent performance, focusing first on the moderating role of prior performance and then on mechanisms through which divestitures by higher and lower performing firms affect performance. The study suggests that divestitures can exacerbate weakness and reinforce strength: Divestitures by lower performers improve profits but inhibit sales growth and tend to speed the firms’ exits as independent actors; by contrast, higher performing divesters invest in support of existing assets and gain new growth, while avoiding becoming acquisition targets. Most generally, divestitures help reduce constraints to changing a firm's resource base, which we refer to as a complementary Penrose effect. Managerial summary Divestitures help both struggling firms and high performers free financial and managerial resources that they can reinvest in more productive uses. In doing so, divestitures reinforce the strength of high performers but may exacerbate weaknesses of struggling firms. Divestitures by lower performers improve their profits but inhibit their sales growth and increase the chances that the firms will be acquired. By contrast, higher performing divesters gain new growth by investing in support of existing and recently acquired assets and, by doing so, are less likely to become targets of acquirers who seek their productive assets. Thus, divestiture is part of a downward cycle for struggling firms but supports a virtuous cycle for superior firms.