Abstract Operational excellence is a dimension of performance conferring competitive advantage to those organizations that sustainably achieve it. However, Operational Implementations (OIs) that are expected to confer such operational excellence to organizations, exhibit variation in their implementation processes and outcomes. Operations Management Practice Contingency Research (OM PCR) has been established in order to understand this. Working within the field of OM PCR, my dissertation focuses on healthcare as an industry and Advanced Access (AA) as an OI for research. I conduct a multiple case study where ten implementation teams represent AA implementations in 23 clinic sites. From this study, I select five cases as my core analytic sample for rigorous investigation. My dissertation contains the results of compiling research documents, interviews with 52 individuals related to healthcare and AA, and a qualitative analysis of the data. The main factors responsible for the variation of implementation processes and outcomes are: • a phenomenon I refer to as task ambulation, which stems from complexity and occurs as a result of movement of the task domain, • lack of appropriate prior technology, • the culture of the implementing clinic prior to implementation, • a phenomenon I refer to as institutional managerial apathy, which manifests as a lack of concern and systematization of a healthcare system, • workload, and related phenomena. I interpret these factors through Contingency Theory, Institutional Theory, and a new theory I developed - the Effort Satisficing Theory (EST). I also propose and elaborate on Task Ambulation Contingency to enhance outcomes of operational implementations. Though this research contributes to a deeper understanding of both AA implementations and OIs in general for both academics and practitioners, the most important contribution of this research to new management and economic theory is the Effort Satisficing Theory, and the establishment of the foundations of this theory. Effort Satisficing Theory is a behavioral theory that can be translated into different fields of management and economics, with potential for advancing the performance of organizations and economies, thus establishing this dissertation a valuable contribution to 21st century Economics.

