1: Introduction. - 1. 1 Background. - 1. 2 Problem Statement. - 1. 3 Research Approach. - 1. 4 Results and Contributions Made. - 1. 5 Outline of Chapters. - 2: A Longitudinal View on Software Development and Participation. - 2. 1 Computer Systems Development: Changing Constraints. - 2. 2 Participatory Design. - 2. 3 Giving the Users What They Want: Effective HCI. - 2. 4 Where Are We Now?. - 2. 5 Research Questions Raised. - 3: The Projects and Their Analysis. - 3. 1 The Development Method. - 3. 2 The Development Projects Studied. - 3. 3 Data Available from the Projects. - 3. 4 Research Method. - 4: Towards a Theory of User-Developer Cooperation. - 4. 1 Developing Interaction Analysis. - 4. 2 The Construction of Shared Understandings. - 4. 3 Cooperative Development and Common Ground. - 4. 4 Conclusion. - 5: Effective Participation: Contributing to Discourse and Artefacts. - 5. 1 The Nature of Participation: Contributing to Discourse. - 5. 2 Were the Studied Projects Participatory. - 5. 3 Effective Participation: Contributing to Artefacts. - 5. 4 Conclusion. - 6: User Participation and Software Usability. - 6. 1 Evaluating the Software. - 6. 2 Summary of the Usability Evaluation Results. - 6. 3 Tracing Relationships Between Contributions Software Features and Usability. - 6. 4 Results of Tracing Analysis. - 6. 5 Discussion. - 6. 6 Conclusion. - 7: Task-Based Cooperative Development: Conclusions. - 7. 1 Summary. - 7. 2 Lessons and Limitations. - 7. 3 Future Work. Language: English