Large and small firms interact in many ways. Different buyer and seller relationships are important for the survival of all firms, and this is probably also the most usual kind of large firm-small firm link. However, especially among high-technology or technology-intensive SMEs, research collaboration and other RTD-related links with large firms ought also to be very important. This chapter focuses on technology-related ownership changes between large and small high-technology firms. These include the spin-off of new SMEs from large firms, intermediate links between large and small firms, and, finally, large firm acquisition of technology-intensive SMEs.