A considerable theoretical and empirical literature studies the corporation's capital structure. Economists have paid less attention to capital structure in other enterprise forms such as partnerships, which typically operate under different legal constraints and appeal to smaller enterprises. Yet partnerships were the dominant business organization for the period in which wealthy countries first experienced long-run economic growth, and they remain quantitatively significant in some important economies today. We use a series of simple models to study several aspects of the partnership's choice of capital structure. We show that common features of partnerships reflect the difficulty of raising capital for ventures whose prospects are hard to judge. We also consider the implications of a rule in partnership law that prevents limited partners from playing a role in management, and the implications of the partnership form for projects subject to hold-up.