We run a field experiment offering graduated microcredit clients the opportunity to finance a business asset worth four times their usual borrowing limit. We implement this using a hire-purchase contract; our control group is offered a zero interest loan at the usual borrowing limit. We find large, significant, and persistent effects: treated microenterprise owners run larger businesses with higher profits; consequently, household consumption increases, particularly on food and children’s education. A dynamic structural model with nonconvex capital adjustment costs rationalizes our results and allows counterfactual analysis; this highlights the potential for welfare improvements through large capital injections that are financially sustainable. (JEL C93, D22, G21, G32, L25, O14, O16)