South Africa has institutionalised the application of combined assurance’s Three Lines of Defence Model (TLDM) through the 3rd and 4th editions of the King Code. Albeit, failure of the TLDM has been documented in recent corporate governance scandals in South Africa. These failures point to the inadequacy of the model in its theoretical underpinnings that place more emphasis on compliance than moral development (acts vs virtue ethics). In this research study, the adequacy of the TLDM was assessed, as well as its effectiveness in dealing with Agency. It was further sought to establish whether competitive advantage could be created through TLDM implementation in South African organisations and to quantify in relative terms, the scope for competitive advantage creation through TLDM application. A mixed research methodology (convergent design) was used to gather quantitative and qualitative insights from governance practitioners in South Africa (concurrently over a cross-sectional time frame). 204 survey respondents and 11 interviewees participated in the study. A statistically valid model for creation of competitive advantage was developed from the quantitative findings while a framework for competitive advantage was developed from the qualitative findings. The findings of the study confirm the inadequacy of the TLDM that it lies in poor implementation by South African organisations than in the model’s theoretical underpinnings. It was concluded that competitive advantage can be created though TLDM implementation in South African organisations, and the scope for creation of competitive advantage is relatively significant. The implementation of TLDM with compliance fixation mediates the creation for competitive advantage through TLDM, while moral development focus in TLDM implementation moderates the relationship between TLDM Adequacy in ethics underpinnings and competitive advantage creation. While the inadequacy of the TLDM was established through this study, the support for the TLDM was still overwhelming, although support for additional levels as contemplated in the Five Levels of Assurance Model (FLAM) was considerable. / Graduate School of Business Leadership / D.B.L. (Strategy and Governance)