Corporate diversification has been a central issue of research concern in strategic management. Previous research basically suggests that a managed diversification may enhance corporate performance. However, few studies illuminate how a firm's operating context affects the relationships between corporate diversification strategies and firm performance. By taking this weakness into research consideration, this paper examines the features of diversification, a firm's operating context and its impacts on economic performance in detail. Using a longitudinal data containing firm-level operation information during 1997-2002, the empirical investigation finds that product diversity and customer diversity are positively associated with firm performance, whereas geographic diversity is negatively associated with firm performance. However, contractual manufacturing model is not only positively associated with firm performance, but also acts as a moderator between product diversity and firm performance. Implications of this result and suggestions for future research are discussed.