Chapter 19 State Longitudinal Data Systems and Public Policy Research George C. Hough Jr. and Vivien W. Chen Introduction In an effort to develop policies related to education and careers, numerous states have developed state longitudinal data systems (SLDS) for the purpose of better evidence-based decision making. These SLDS offer promise for supporting policymaking and research beyond meeting federal and state data reporting require- ments, yet may not answer many of the most pressing research questions nor create meaningful collaboration between researchers and practitioners (Conaway et al. 2015). With SLDS, the collection and organization of data across time provides a more dynamic approach to analysis than was previously provided by the cross-sectional data reported from the school district to the state education agency to the federal government. In addition, much of the data were contained in data silos representing various programs. Therefore, data had to be linked across these silos to get a complete story of a student’s participation. Finally, SLDS developed linkages to perform cross-sector research and evaluation. K-12 data were linked to early learn- ing, postsecondary education and eventually workforce participation. The Washington state Education Research and Data Center (ERDC) developed their G. C. Hough Jr. (*) Education Research & Data Center, Office of Financial Management, Olympia, WA, USA e-mail: George.Hough@ofm.wa.gov V. W. Chen Education Research & Data Center, Forecasting & Research Division, Helen Sommers Building, Olympia, WA, USA e-mail: Vivien.Chen@ofm.wa.gov © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020 B. Jivetti, Md. N. Hoque (eds.), Population Change and Public Policy, Applied Demography Series 11, https://doi.org/10.1007/978-3-030-57069-9_19 365