Addressing the problem of access versus ownership and surveying uses of ILL data in collection assessment, this paper argues for a model of access-informed collection development that brings subject analysis and just-in-time acquisitions together into a single, unified method. Drawing upon the work of John Ochola, this paper articulates a method of subject analysis that combines holdings, circulation, and ILL data to determine the use characteristics of particular LC subclasses. It then combines this access-informed subject analysis with just-in-time acquisitions. This paper argues that access-informed subject analysis improves on assessment methods that do not include all three variables, and that just-in-time acquisitions augments subject analysis by providing selection guidance beyond the level of LC subclasses, as well as discrete, measurable feedback on selection decisions.