In 2016 the Archaeology Data Service (ADS) was 20 years old. Since its birth the ADS has had to respond to rapid changes in technology, as well as major cultural and organizational changes in the external operating environment, from which a sustainable business model for digital preservation has emerged. This article will take a retrospective look at challenges that have been faced and will review current and future priorities for those seeking to establish digital repositories. Digital preservation and open access to research data are now much higher up the agenda of funding bodies, but there is still lack of agreement on what constitutes a core digital archive from a fieldwork project. The paper will review what the significant properties of an archaeological archive are, and how reuse can be supported, linking data and publications. It will consider the challenge of dealing with the gray literature and of avoiding creating further data silos, featuring new initiatives to provide interoperability between digital repositories. It will review the role of data and metadata standards, and consider how the profession needs to address its responsibilities over the next 20 years.