Purpose of the study: This research examines the major organisation strength factors, important project management competencies, and the criteria for project success, and their interrelationship. Methodology: A mixed-method approach is applied with a positivist stance to test the validity of the proposed hypotheses. Based on the detailed literature review and five expert interviews, 'organisation strengths' are identified and classified into three subcategories, making a second-order construct. A survey strategy is used to collect data from PMO individuals of construction organisations. SmartPLS software is used to analyse 97 responses. Main Findings: The results of this study support the proposed relationship. It suggests that organisation strengths influence project management competencies and project success. Furthermore, resources and capabilities influence project success. The findings are in line with the literature suggesting that organisation resources and capabilities are important for project success. Application of the study: This study is relevant for PMO individuals, especially in construction organisations. The findings highlight the importance of organisational strengths that lead to build project management competencies and eventually attain project success. These organisational strengths are of great significance to both the researchers and industry practitioners. The originality of the study: This study has applied a mixed-method approach. The model in the study empirically tests the organisation strength factors affecting project success. Furthermore, the study used SmartPLS software to test the influence of organisation strength to increase project management competencies and their cumulative effect on project success.