This paper analyzes the evolution of the Spanish economy during the third quarter of the 19th century, the critical initial phase of its modern development. The specific aim of the paper is to discuss the role to be awarded to foreign and domestic capital in financing the investment boom in those years. The main hypothesis stresses that the mobilization of savings previously accumulated and hoarded in gold was a distinctive and important origin of resources. This result challenges older assumptions about the economic changes of the period, and provides a vision somewhat different of the first steps of Spain's economic modernization.