There is a widespread idea that corporations have completely taken over invention and innovation processes throughout the twentieth century, thus becoming the main users of patent systems. However, recent studies suggest that, in spite of corporate expansion, independent invention is still economically significant nowadays, and that individuals outside the boundaries of the firm were actually the principal source of innovation before World War II. This article analyzes the history of corporate and independent patents in Spain in the long-term, in order to confirm that independents were also very relevant to promoting innovation and technology transfer in latecomers with high rates of technological dependence. Employing a new method of work with patent files, we also offer new historical evidence of the structure, effectiveness and scope of emerging international social networks of innovation. After introducing the research framework, Section Two briefly summarizes the characteristics of the Spanish patent system, and compares corporate and independent patents taken out between 1820 and 1939. Section Three studies the duration and strength of independent patents and the structure of the communities of innovation, and the conclusions make up Section Four.