Organisational development is a contractual relationship between a change agent and a sponsoring organisation entered into for the purpose of using applied behavioral science in a systems context to improve itself. Organisational development is one of the most significant developments in the fied of organisational behavior in recent years. Organisational behavior began to evolve as a distinct field os study in the 1940's when behavioral scientists in the US and Britain made efforts to resolve problems facing modern organisation. It has been defined in different ways by different behavioral scientists and applies the knowledge and practice of behavioral science to improve the effectiveness of organisations.