Knowledge Management Software must be embedded in processes of knowledge workers' everyday practice. In order to attain a seamless design, regarding the special qualities and requirements of knowledge work, detailed studies of the existing work processes and analysis of the used knowledge are necessary. Participation of the knowledge owners and future users us an important factor for success of knowledge management systems. In this paper we describe characteristics of knowledge work motivating the usage of participatory design techniques. We suggest a design process for developing or improving knowledge management, which includes ethnographic surveys, user participation in cyclic improvement, scenario based design, and the use of multiple design artifacts and documents. Finally we explain the benefits of our approach. The paper is based on a case study we carried out to design and introduce a knowledge management system in a training company.