ABSTRACT This article makes a contribution to the study of family groups in developing economies by analysing the case of the Cousiño-Goyenechea business, one of the most important business groups in nineteenth-century Chile. We provide new evidence of how the Cousiño's original fortune was built, and how after being highly concentrated in copper and silver mining, the family business successfully diversified and integrated vertically through two generations, thus becoming the second most important economic group in the country by the end of the 19th century. This was the result of risky business decisions, particularly after deciding to enter coal mining under much uncertainty, modernising this industry, as well as expanding into copper refining, brick and glass manufacturing, hydroelectric power plants, and wine production. However, their success was also due to a clever strategy of capital increase by creating corporations linked to the group.