ADEPT MODELS AND TOOLS ADEPT is a novel design environment for prototyping user interfaces which allows the designer to construct an explicit model of the tasks that the user and computer witl perform jointly. ADEPT incorporates task and user modelling components with a rapid prototyping user interface design tool to provide a user-task centred design environment. ADE~ encompasses design from task analysis to the generation of a run-time system through a number of modelling stages (Figure 1). The environment provides editors, browsers, interpreters and generators that atlow each of the models to be functionally employed in user interface design. The task modelling component of ADE~ provides the designer with a graphical editor which allows the designer to construct and browse models of the existing and proposed tasks described in terms of Task Knowledge Structures [1]. The output from the task modelling component feeds directly into the Abstract Interface Model (AIM) component. The AIM provides the designer with a high-level specification of the interaction, expressed in terms of the dialogue structure and abstract interaction objects. The designer can edit and elaborate the AIM using the editors and browsers of ADEIT. The Concrete Interface Model (CIM) is a platform independent description of the interface design at a detailed level of interaction objects, their behaviour and screen layout. A generator tool creates a default CIM which the designer can edit using the CIM tools. The generator is influenced by input of user centred design characteristics from the User Model. The user model is a rule base of design principles which are tailored by the designer with facts concerning the details of the intended user group. The interaction between the CIM generator and the User Modelling components is in the form of question/answer dkdogues which are carried out automatically during the generation process. The CIM may be translated into a platform dependent implementation which makes use of a standard widget set such as Open Lookm. Other platforms can be accommodated by writing alternative translators. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of tha publication and ite date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fea and/or specific permission.