3Systems Concepts in Action: A Practitioner's Toolkit explores the application of systems ideas to investigate, evaluate, and intervene in complex and messy situations. The text serves as a field guide, with each chapter representing a method for describing and analyzing; learning about; or changing and managing a challenge or set of problems. The book is the first to cover in detail such a wide range of methods from so many different parts of the systems field. The book's Introduction gives an overview of systems thinking, its origins, and its major subfields. In addition, the introductory text to each of the book's three parts provides background information on the selected methods. Systems Concepts in Action may serve as a workbook, offering a selection of tools that readers can use immediately. The approaches presented can also be investigated more profoundly, using the recommended readings provided. While these methods are not intended to serve as recipes, they do serve as a menu of options from which to choose. Readers are invited to combine these instruments in a creative manner in order to assemble a mix that is appropriate for their own strategic needs.