The Stockholm International Peace Research Institute (SIPRI) has long been researchers' primary source for countries' military expenditure data. For the most part, the data were limited to the time period from 1988 onward. Now, SIPRI is releasing revised and backdated data for, in most cases, 1960 onward. The articles in this issue of EPSJ examine the new data and use them for comparative studies relative to the use of the "old" SIPRI data. By way of introduction, the lead article by Sam Perlo-Freeman and Elisabeth Sköns, the previous and current leaders of SIPRI's military expenditure data project, relates the history of SIPRI's military expenditure data construction. Gulay Gunluk-Senesen compares the "old" and "new" SIPRI data for the cases of Greece and Turkey. So does Eftychia Nikolaidou, but for Greece, Portugal, and Spain and with an emphasis on reexamining the nexus between miltiary expenditure and economic growth, especially in light of the post-2008 global financial and EU-debt crises. Christos Kollias and Suzanna-Maria Paleologou broaden the scope to study the EU15 countries, focusing on growth, investment, and military expenditure. Julien Malizard also studies the EU15, focusing on military versus nonmilitary public expenditure. Mohamed Douch and Binyam Solomon broaden the scope even further, to eleven Middle Power countries. Finally, J. Paul Dunne and Nan Tian include nearly 100 countries in their comprehensive and comparative study of military expenditure and economic growth with the "old" and "new" SIPRI data.