User participation is a key element in user centered design of interactive systems. However, applying established methods is not straightforward while realizing a system for people with cognitive impairment due to their specific, heterogeneous needs and abilities. This paper presents experiences from conducting a user centered inclusive design process within an ongoing project. It aims at the development of a web application for people with dyslexia caused by cognitive impairment. A distinctive feature is the intended use of the application: It must support the counseling interviews for planning the real life inclusion of the target group. In addition, it must enable cognitively impaired as well as non-impaired people using it cooperatively. One of the most challenging issues was how and when to involve cognitively impaired users.