This article summarizes key points made in a session at the American Society of Criminology meeting in Philadelphia in November 2017, entitled “The replication issue in science and its relevance for criminology”, organized by Friedrich Lösel and Robert F. Boruch. In turn, this session was inspired by Friedrich Lösel’s (2018) article in this journal, based on his 2015 Joan McCord Award Lecture of the Academy of Experimental Criminology. In the present article, Friedrich Lösel introduces the topic of replication in criminology and summarizes his main arguments. Then, six leading criminologists present short papers on this topic. Robert F. Boruch points out the instability in social systems, David P. Farrington argues that systematic reviews are important, and Denise C. Gottfredson calls attention to the heterogeneity in conclusions across different studies. Lorraine Mazerolle reviews attempts to replicate experiments in procedural justice, Lawrence W. Sherman draws attention to enthusiasm bias in criminal justice experiments, and David Weisburd discusses the logic of null hypothesis significance testing and multi-center trials. Finally, some developments since November 2017 in research on replication in criminology are discussed.