Aid for trade increases a recipient's public services, which lower its import and export transport costs. Formulating a two‐country endogenous growth model, we obtain two main results. First, a permanent increase in the donor's aid/gross domestic product (GDP) ratio raises the steady‐state growth rate as well as both countries' long‐run fractions and cost shares of imported varieties if and only if it lowers the product of transport costs. Second, under a plausible condition, there exists a unique interior growth‐maximizing aid/GDP ratio. These results are robust to alternative specifications for congestion and stock‐flow nature of public goods.