Nowadays, most of the research developed by industry and academy has led to several object-oriented methods highly adequate for the development of systems. But most of these methods do not include mechanisms (models) for identifying and specifying user needs and requirements us well us testing and vuliduting requirements with end-users before, during and after development. These considerations are specially important in interactive systems, where the user interaction is very high and the user interface is a significant part of the system. As a result of this weakness, interactive systems developed using such methods can meet all technical requirements, be very robust, and yet be unusable by the end-user. This problem explain a large purt of the frequently-observed phenomenon whereby large numbers of change requests to modify the services of an application are made afier its deployment. As a solution to this problem we propose a method for integrating a user interface model, taking into account user needs and requirements, into the software life cycle. Besides, this approach to the development process ensures the quality of the delivered applications from the point of view of the end user.