Functional integration is the compatibility between the structure, culture and competence of an organization and its computer systems, specifically the availability of data and functionality and the consistency of user interfaces. Many people use more than one computer program in their work, and they experience problems relating to functional integration. Various solutions can be considered for different tasks and technology; e.g. to design a common userinterface shell for several applications, or to merge the user programs. The solutions may require different types of technical integration. Object-oriented methods for application development are said to be well suited for developing components that are useful in several applications. A framework for capturing functional integration in object-oriented analysis and design is proposed. The framework distinguishes between the users, the parts of the computers that are perceivable during use, and the inner parts of the computer system. In addition, distinctions between layers of implementation are introduced. It is demonstrated how object-oriented models of information systems should be modularized according to the framework. Typical solutions are characterized by object-oriented models in the framework, including the shell and copy and paste. Three object-oriented approaches are examined to see whether they address problems of functional integration. It is found that none of these approaches cover all relevant aspects.