This paper considers the implications of the growing trend for Engineer-To-Order (ETO) companies to engage in projects that involve not just the design and manufacture of capital plant and equipment, but also responsibility for downstream aspects of the project such as operations, maintenance and service delivery. These types of long-term, service-focused projects introduce an added dimension of complexity to the project that stems from a proliferation of stakeholders and multiple customers within the project. Drawing on three detailed case studies of projects with a long-term, service focus, this paper explores the problems facing ETO companies and their project managers in terms of identifying who the critical customer is at any particular stage of the project and highlights some implications for the management of the design and innovation process in such ETO projects.