Services are a dominant component ($55352bn of worldwide GDP) in the global economy (Worldbank, 2016). Self-service transactions have a significant economic impact (Castro et al., 2010) in most sectors of the service economy.  These transactions are co-productive services (Normann, 2001), customers provide inputs and resources (Sampson and Froehle, 2006). Service providers receive the benefits of these transactions. Providers, design services to achieve outcomes and engage customers in co-productive work.  This transdisciplinary research explores three components of service design, the service process (Sampson and Froehle 2006), the service concept (Goldstein, Johnston et al. 2002) and service encounter (Solomon, Surprenant et al. 1985), the service strategy triad (Roth and Menor, 2003). Self-service transaction outcomes of efficiency and effectiveness for the provider depend on service design. Customer contact theory (Chase, 1978, Chase, 1981) suggests service designs should have low customer contact to reduce variation to achieve efficiency. Self-service increases customer contact, this theory suggests efficiency reduces. The growth of self-service is unlikely if provider efficiencies reduce, because of the impacts on productivity. This gap in service design theory and practice was acknowledged by (Chase, 2010). Service design research is lagging behind practice in rapidly changing contexts (Ostrom et al., 2015), this thesis explores these gaps with embedded case studies  on service transactions. \ud
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The findings from this research build service design theory. Customer contact theory is refuted and reconceptualised. Service design characteristics are identified to ensure efficiency. The role of mediating technology is to replace service workers, provide process control, and reduce variation to achieve process efficiency. A recent service design and process visualisation methodology (Sampson, 2012) is validated. These contributions advance service operations management research, provide a theoretical base for further research in other contexts and have significant implications for practitioners for improving productivity