Research Libraries have a long history of studying the users of their collections, but these theories and methods have not translated easily into stud- ies of digital services, much less of digital data services. By combining information from DANS transaction logs with a user database we gain insights into who uses the archive and how. Curation Images form the largest part of the archived ﬁles. Most of them stem from archeological data- sets. One of the biggest challenges in long-term preserva- tion is to still be able to read/display digital content - ﬁle type recognition is a prerequisite. Monitoring of the amount of datasets, their composition in terms of ﬁles, ﬁle size, and ﬁle type is needed to design strategies for storage and access. Here we show a polar bar chart of mime type frequencies (above) and the growth of the archive (below). Datasets with a later creation date have more ﬁles, and there are more datasets each year. Before 2000 the archive grew yearly by less than 2 GB. After 2000 we observe a dramatic change in the growth regime, adding between 100 and 500 GB each year. Navigation From the transactions logs, we extracted the 70 most frequently used search terms across all sessions. Clustering strings reveals groups of topics: archeological sources (see cluster 1-4), elections (*kiezer*), mobility (*mobiliteit*), or living conditions (*woon*). OPACs (Online Public Access Catalogue) determine how the user sees the collections of a digital library or archive. Visualizations of a collection can bridge the gap between the old physical and the new digital. But what to visualise? Geographic regions and periods in time? The interconnectedness of search terms and their possible targets or the composition of the collection in terms of targeted audiences? As of May 2015, EASY contains 29,743 published datasets (the equivalent of a “collection” in Dublin Core ). The majority of submitted datasets originate in archaeology, for which EASY is a legal deposit archive. The majority of downloaded datasets are from the social sciences. See a showcase of a visual exploration of EASY at: http://www.drasticdata.nl/projects.htm#DansEasy Christine Borgman, Andrea Scharnhorst, Henk van den Berg, Herbert Van de Sompel, Andrew Treloar christine.borgman@ucla.edu, andrea.scharnhorst@dans.knaw.nl, henk.van.den.berg@dans.knaw.nl, herbertv@lanl.gov, andrew.treloar@ands.org.au Surprisingly little is known about the uses and users of digital data archives, about relationships between users and the staﬀ of data archives, or how these behaviors vary by discipline, geographic region, policy, and other factors. Digital data archives are not a single type of institution - they vary widely in organizational structure, mission, collection, funding, and relationships to their users and other stakeholders. We present an exploratory study of EASY, the Electronic Self-Archiving SYstem, a digital archive hosted at DANS. DANS was founded in 2005 as an institute of the Royal Netherlands Academy of Arts and Scienc- es (KNAW) and of the Netherlands Organisation for Scientiﬁc Research (NWO). DANS is responsible for archiving 50 years of digital research data in the social sciences and humanities. We present a number of visual explorations with the goal of identifying methods for studying the contributors, consumers, and role of archivists in digital data archives. In particular we address RESEARCH about users; CURATION of digital content, and interfaces for NAVIGATION. [1] Christine L. Borgman, Andrea Scharnhorst, Henk van den Berg, Herbert Van de Sompel, and Andrew Treloar. "Who Uses the Digital Data Archive? An Exploratory Study of DANS" Information Today (2015). ! magnitude: 1000, 100, 10, 1 users sessions Number of logged in users and sessions, world!wide, 2011 ! 2014 ! magnitude: 1000, 100, 10, 1 users sessions Number of logged in users and sessions, 2011 ! 2014 !"##$"%&' (#$)* *+,-.(%$, -..+-.++*-" /-#'. .$.)#0".+-.#1%!"*-%0.)#%'#$!%. .-01#*)*,%# .-01.#*)