There is an emphasis on user participation in social work. The arguments derive from both a democratic and a consumerist approach, aiming on the one hand to equalize power between users and professionals, and on the other hand, for more efficient and legitimized services. However, research shows that there is a lack of knowledge about methods and conditions for realizing user participation in social services. In this exploratory study, grounded in participatory design, a set of four workshops took place, enabling young people, social workers and researchers to participate in the design process. The data were analysed with affinity analysis, a technique whereby the data are sorted with “I” labels, to stay close to the material. Also, written feedback and reflections from participants as well as oral feedback and reflections were generated, documented and integrated with the affinity analysis. The main findings concern how the participatory approach revealed tensions between the participants’ different perspectives on user participation, which in turn contributed to the shaping of a dynamic tool. The findings imply that the tool needed to be both “fair and square” to ensure equality for all young people, and dynamic and flexible to meet the uniqueness of each young person. Moreover, the tool needed to be both rich and contextualized to meet the need for information and participation throughout the transition process, and simple and accessible to meet the acute nature of many transitions as well as the overall time constraints within social work practice. The research process reached the level of contribution, with involvement in some but not all stages labelled as collaboration. The wide range of expertise involved in the design process provides a good basis for the tool to be able to address the need for increased user participation in social work practice.