As higher education quality assurance in many countries in Europe has become a mature activity, some agencies carrying out external quality assurance are developing beyond their core tasks and missions. The current study identifies new tasks taken up within quality assurance agencies and analyses the drivers behind such development. Based on an empirical investigation into six quality assurance agencies in Europe, the study finds that these agencies are still under substantial control of and influenced by national authorities--often resulting in new tasks and responsibilities that are added to older tasks and established responsibilities. The ongoing innovations can be characterized by two dynamics: 'bounded innovation' where new tasks and activities are induced by public authorities, and agency drift where agencies themselves redefine and expand existing tasks and activities. The developments also show a high degree of diversity, suggesting that mature quality assurance agencies do not develop on a convergent path.