With this issue, topiCS begins its fifth year of on time publication of innovations of advanced research and commentaries of concern to the Cognitive Science community. This issue of topiCS contains three topics. Our new topic is “Why Formal Learning Theory Matters for Cognitive Science.” This topic has been organized and edited by Sean Fulop (CSU, Fresno) and Nick Chater (The University of Warwick). Formal Learning Theory is based in what most cognitive scientists would consider “difficult mathematics.” Although these mathematics provide the strength and generality of the approach, they also present a formidable barrier to most of the community. In this topic, Fulop, Chater, and their many contributors have striven to put the concepts and results first, and the mathematics second. The result is a set of interesting and exciting papers in which the mathematical achievements of the work, and their implications for cognitive theory, are made clear. The second topic continues our annual tradition of publishing the “Best Of” papers that have appeared in recent cognitive science conferences. We began by considering the set of papers that had won awards at the Sapporo 2012 Cognitive Science Conference. Members of the Senior Editorial Board read each paper and recommended for publications those that “made good journal papers.” The result is a strong collection of diverse, interesting, important, and short papers that should interest many of our readers. In July's issue (volume 4 issue 3), we published Addyman and French's paper: “Computational Modeling in Cognitive Science: A Manifesto for Change.” This paper has already excited some interest and support from the community as well as discussions of other changes that we should embrace. In this issue, Tang and Pitt (OSU) extend that discussion to ask, “What Should Be the Data Sharing Policy of Cognitive Science?” These discussions are useful and hopefully will result in change for the better in how our community conducts its science. We encourage feedback from our readers on both of these papers in the form of short letters to the Editor or slightly longer commentaries. topiCS encourages commentaries on all topics and proposals for new topics. Send your commentaries directly to me at grayw@rpi.edu along with a short note. If you are proposing a topic, please open communications with a short first note (about 300–650 words or fewer) and be sure to consult the topiCS FAQ page, http://csjarchive.cogsci.rpi.edu/topiCS/FAQs.html, for Preparing a Proposal for topiCS.