This book describes version 4 of CATS CM®. This methodology for contract management can be used in both private and public sector organizations, and is valid for both demand and supply side. Contract management is the realization of intended contract objectives by proactively monitoring the fulfillment of all contractually established responsibilities, obligations, procedures, agreements, conditions and rates, resolving all ambiguities, contradictions and white spaces, managing all contract-related risks, and implementing all desired changes to the contract, during the execution phase. CATS CM® offers a methodical and scalable approach to contract management. It provides a description of the principles, roles, and main issues for the contract manager and the best way of working. In addition to a description of the methodology, CATS CM® version 4 also offers specific tools for implementing contract management, for policy as well as for processes. Increasingly, organizations recognize the importance of being in control of their business ecosystem. CATS CM® assists organizations to increase control of their joint responsibility both from a procurement and delivery point of view. A large number of organizations have chosen CATS CM® as the standard for their contract management processes. This new version of CATS CM® has been developed with these various practices in mind. CATS CM® version 4 is based on the principle that the management of a contract in execution has strong similarities on both sides of the contract, i.e. demand and supply; both can best be described as working in conjunction with each other. This book is intended for all who are responsible for, or deal with the execution of contracts: contract managers, business managers, delivery managers, project managers, service managers, facility managers, buyers, procurement managers, compliance managers, risk managers, account managers, sales managers and HR managers, along with their directors and board members on both sides of the contract.