Firms and analysts jointly shape the corporate information environment, yet most existing theories examine their roles in isolation. We develop a game-theoretic model, in which their information-acquisition investments are strategic substitutes (in the sense of Bulow et al. 1985), and disclosures are voluntary. In equilibrium, an increase in one party’s information quality crowds in its information acquisition and crowds out the other’s acquisition, whereas greater cash flow uncertainty can induce both to invest more in information acquisition. These results reconcile mixed empirical findings on whether firms and analysts play substitutive or complementary roles. The firm’s disclosure frequency increases with its information quality, decreases with the analyst’s information quality, and can be nonmonotonic in its cash flow volatility. Price efficiency typically increases with the qualities of the analyst’s and the firm’s information, but it is nonmonotonic in the firm’s cash flow volatility due to the indirect effects implied by strategic substitutability. Overall, our results provide new insights into the literature.