This fourth edition of "Simulation with Arena" has the same goal as the first three editions: to provide a comprehensive treatment of simulation concepts in general and the Arena simulation software in particular. It starts by having the reader develop simple, well-animated, high-level models, and then progresses to advanced modeling and analysis. Statistical design and analysis of simulation experiments is integrated with the modeling chapters, reflecting the joint nature of these activities in good simulation studies. The objective is to help the reader carry out effective simulation modeling, analysis, and projects using the Arena simulation system. An informal, tutorial writing style is used to aid the beginner in fully understanding the ideas and topics presented. Included is a CD containing the current version of the Arena academic software and the examples referenced throughout the text. Starting with an introduction to simulation concepts, the book progresses through an overview of the Arena software, basic model development, input analysis, additional modeling constructs, output analysis, and advanced modeling. It also includes chapters on integrating Arena simulation models with other applications, specialized statistical issues, continuous simulation, and conducting a successful simulation study. It is intended primarily to be a text in a first course on simulation or for self-study. However, the later chapters could be incorporated into an advanced or graduate-level course. Building on the success of the first three editions, published in 1998, 2002, and 2004, this edition retains the basic outline and tutorial style, built around a sequence of successively more complicated examples. All the examples and discussion, however, have been modified and updated to be consistent with the current version of the Arena software, and additional examples have been developed, along with more exercises. As before, a password-protected website for instructors provides support in terms of downloadable lecture slides and solutions to end-of-chapter exercises. The book draws heavily on the experience and expertise of the authors, a professor at the University of Cincinnati specializing in simulation, and two seasoned members of Rockwell Software (formerly Systems Modeling), the developers of Arena, who are active in product design and development, training, consulting, and applications.