For college and research libraries, a major 21st century transformation has been the spending shift from print materials to electronic resources. This shift has triggered ongoing conversations about resource allocation at many institutions. Common assumptions that are drawn from these general trends: • Spending on the sciences has increased at the expense of the humanities • Spending on serials has increased at the expense of monographs Overly simple expenditure codes that merely distinguish print from electronic do not allow these assumptions to be tested. This poster will demonstrate how a 2013 revision of expenditure codes used in the library’s acquisitions system provided more granular distinctions among e-resources, thus revealing new trends in collection development. Data visualizations will show the growth in new formats, such as digitized archives and datasets; charts and graphs will also tell a story of analog formats in the 21st century. The poster will engage the audience with questions: • How can libraries categorize spending to allow for comparability over time yet allow for flexibility as new formats emerge? • How can individual libraries devise categories that will be interoperable and comparable with other libraries in collaborative networks? • What other metadata can we bring to bear on our understanding of collection expenditure trends over time?