This book summarizes the new research results presented at the 12th Joint Conference on Knowledge-Based Software Engineering (JCKBSE 2018), which took place on August 27–30, 2018 on the island of Corfu, Greece. The JCKBSE is a well-established international biennial conference that focuses on the applications of Artificial Intelligence in Software Engineering. The JCKBSE 2018 was organized by the Department of Informatics of the University of Piraeus, the Department of Computer and Information Engineering of Nippon Institute of Technology, and the Department of Informatics of Ionian University. The book will benefit not only experts and researchers in the field of (Knowledge-Based) Software Engineering, but also general readers in the fields of Artificial Intelligence, Computational Intelligence and Computer Science who wish to learn more about the field of (Knowledge-Based) Software Engineering and its applications. An extensive list of bibliographic references at the endof each paper encourages readers to probe further into the application areas that interest them most.