Almost two thirds of the cross-plant dispersion in marginal revenue products of capital occurs across plants within the same firm rather than between firms. Even though firms allocate investment very differently across their plants, they do not equalize marginal revenue products across their plants. We reconcile these findings in a model of multi-plant firms, physical adjustment costs and credit constraints. Credit constrained multi-plant firms can utilize internal capital markets by concentrating internal funds on investment projects in only a few of their plants in a given period and rotating funds to another set of plants in the future. The resulting increase in within-firm dispersion of marginal revenue products of capital is hence not a symptom of misallocation within the firm, but rather actions taken by the firm to mitigate external credit constraints and adjustment costs of capital. Economies with multi-plant firms produce more aggregate output despite higher dispersion in marginal revenue products of capital compared to economies with single-plant firms. Because emerging economies are predominantly populated by single-plant firms, the gains from reducing their distortions to the level of developed are larger than previously thought.