Five years after their public launch, Creative Commons licenses have achieved impressive adoption across many different content types, users, and jurisdictions. However, this adoption has proven difficult to characterize, in part due to its decentralized nature. This talk will give a brief overview of what we know about quantitative and qualitative growth of CC license adoption, upcoming initiatives to increase this knowledge and to make raw data on CC license usage more available to researchers, and the role of CC technology efforts in facilitating adoption metrics, including reuse tracking.