This paper explores the quantitative link between export-promoting commercial policies and economic growth. We build and calibrate a dynamic general equilibrium model of a small developing economy. The economy’s equilibrium is suboptimal due to monopolistic competition in the manufacturing sector and a human capital accumulation externality. Second-best commercial policy that promotes exports in the sector with the externality can lead to an increase in both welfare and growth rates. We show that export-promoting policies can lead to substantial quantitative increases in steady-state growth for a wide range of parameter values.