This thesis investigates how a relational co-creative research approach impacts service design practice and thus aims to contribute to expand the understanding of service design and its value. The thesis draws conclusions from a case study, of which the design process explores the challenges of dementia family caregivers in the Danish welfare system. The case results in a report highlighting the insights and opportunity spaces on how to improve the support of dementia family caregivers. The case study employs an approach inspired by the Feed Forward methodology, and is structured in activities that ensure a relational and co-creative focus. The research suggests alternative methods, such as conversations, stories and a collective evaluation, as a way to extensively involve participants in a service design project. The approach reveals to challenge the role of service designers, stressing the need of resources and capabilities, such as the ability to support participants in emotionally difficult situations, that designers are not necessarily taught. Furthermore, the research shows that everyone involved in the service design process is to be understood as an expert – the participants as the experts of the theme, and the designers as the expert of supporting others in designing. The thesis reveals that relations between participants in a service design project that are characterised by trust, sensitivity and empathy are beneficial for a co-creative research process, as they ensure engagement and contribute to mobilise participants’ reflections, making them think and act in ways that are more beneficial for them. These relations can be fostered by building safe, informal and authentic design environments. Thus, the thesis expands the understanding of service design as not only being a means to design services, but shows that the design process in itself is valuable, as it contains a transformative power. Based on the research, the thesis formulates assumptions about the approach and thus offers a foundation for future research.