Despite the progress in recent decades, one in ten people globally still live in extreme poverty, and this number is set to increase in the coming years. Designing interventions to improve well-being and livelihoods is challenging because poverty is multidimensional and plays out in complex, adaptive social-ecological systems, where behaviours and practices at the local level can have unintended consequences elsewhere in the system. In such contexts, linear approaches to designing development interventions are insufficient. Service design has emerged as a human-centred, integrative approach to designing services and systems in complex settings, but knowledge gaps remain on how service design can be used to address development challenges in the Global South. Without an understanding of how service design tools and approaches function in these contexts, there is a risk they might inadvertently cause harm to research participants and local communities.

This thesis contributes new knowledge about how service design can be used to design development interventions in complex social-ecological contexts The research questions address three areas where service design could play a role: (i) how service design could be used to make sense of local level complexity and package this information for development programmers and policymakers; (ii) how service design could support local agency in the design of development projects; and (iii) how service design could be used to complement conventional methods of development research.

The research questions were addressed using three case studies of development interventions. In two of the cases, a clean cookstove intervention in Kenya and an insurance product for small-scale farmers in Uganda, a service design approach was combined with quantitative methods. In the third case study, participatory backcasting was used to inform a long-term plan for energy transition for an off-grid community in Machakos, Kenya. A conceptual framework was first developed to support the use of service design to address development challenges in complex social-ecological systems. Elements of the framework were then applied in two of the case studies: the cookstoves and insurance studies. The thesis uses service design as an approach and practice, and the capabilities approach as the main conceptual and theoretical framing.

The findings reveal that in these contexts, service design tools can become devices for understanding how value is assigned over time by users of the designed services. Archetype construction and prototyping became important devices for identifying patterns in heterogeneous needs and behaviours, while conveying key design parameters to policymakers and programmers. The research also shows that prototyping can enhance local agency by allowing research participants to challenge the core assumptions that underpin proposed interventions. The findings also demonstrate that participatory backcasting can be positioned as a device for prototyping future development pathways. It was found to facilitate individual and collective action in the short term. Combining service design devices with quantitative methods allowed triangulation of findings and a more comprehensive understanding of complex contexts.

Beyond the empirical findings on design devices, the thesis makes two important conceptual contributions. First, it positions service design as an integrative approach to conducting transdisciplinary development research in complex social-ecological contexts. Second, the thesis bridges service design and the capabilities approach and demonstrates how this can help designers anchor their work in the local context while navigating normative development objectives. The contributions are useful for service design researchers and practitioners interested in how service design can be used alongside other disciplines to support long-term development objectives. For the development community, the contributions demonstrate a radically different approach to designing interventions where complexity, messiness and non-linearity are embraced.