A practical guide to building computational models of high-level cognitive processes and systems. High-level processes are those central cognitive processes involved in thinking, reasoning and planning, and so on. These processes appear to share representational and processing requirements, and it is for this reason that they are considered together in this text. The book is divided into three parts. Part one considers foundational and background issues. Part two provides a series of case studies spanning a range of cognitive domains. Part three reflects upon issues raised by the case studies. All models discussed in this book are developed within the COGENT environments. COGENT provides a graphical interface in which models may be sketched as box and arrow diagrams and is both a useful teaching tool and a productive research tool. As such, this work is designed to be of use to both students of cognitive modelling and active researchers.