This book contains selected papers on language, application, and environment of CafeOBJ, which is a specification language state-of-the-art algebra. The workshop attracted about 30 talks and more than 70 participants. The papers in the book, however, whether the revised version was presented at the workshop, to reflect the latest progress or research, or completely new, written especially for this book. Also, although this is a summary of the papers associated with CafeOBJ, this book is no manual, reference, or tutorial of CafeOBJ. Reflecting the diverse nature of projects and participants (the majority of participants to the project author), paper, collect, offers a comprehensive overview of the methodological perspective. Several papers dealing with various aspects of advanced languages, such as rewriting logic and behavioral logic. In particular, UML, now considered the de facto standard language for system modeling, is the subject of one paper. Some papers shed new light on the more traditional paradigm in that language; order sorted equational specifications. Another paper by the environmental agreement to writing and vertifying specification written in CafeOBJ.