In this paper we introduce new expert-coded measures of regime legitimation strategies for 179 countries in the world from 1900 up until 2018 that are comparable across time and space. Country experts have rated the extent to which the government promotes or references its performance, the person of the leader, rational-legality, and ideology in order to justify the regime in place. With regards to ideology, the experts are further asked to categorize the ideology of the regime as nationalist, communist/socialist, conservative/restorative, religious, and/or separatist. The main purpose of this paper is to describe and validate the data against expectations on claims from case studies as well as with existing regime type classifications. We show that experts do understand and can be employed to code legitimation claims. Not only do we document historical shifts in legitimation claims, but the measures also pick up recent trends, such as, an increased emphasis of the leader in countries such as Russia, Turkey, Cambodia over the last decades, and more recently also in India and the Philippines; as well as recent increases in legitimation claims based on both conservative and nationalist ideologies the European countries Serbia, Hungary and Poland, which also have experienced autocratization in recent years.This research project was supported by Riksbankens Jubileumsfond, Grant M13-0559:1, PI: Staffan I. Lindberg, V-Dem Institute, University of Gothenburg, Sweden; by Knut and Alice Wallenberg Foundation to Wallenberg Academy Fellow Staffan I. Lindberg, Grant 2013.0166, V-Dem Institute, University of Gothenburg, Sweden; as well as by internal grants from the Vice-Chancellor’s office, the Dean of the College of Social Sciences, and the Department of Political Science at University of Gothenburg. We performed simulations and other computational tasks using resources provided by the Notre Dame Center for Research Computing (CRC) through the High Performance Computing section and the Swedish National Infrastructure for Computing (SNIC) at the National Supercomputer Centre in Sweden, SNIC 2017/1-407 and 2017/1-68. We specifically acknowledge the assistance of In-Saeng Suh at CRC and Johan Raber at SNIC in facilitating our use of their respective systems