One of the main capital expenditures is construction projects; these can provide very large profits. These profits can be used for public projects; that are justified by cost-benefit analysis, or private projects; that are justified by budget constraints. Most projects have a very tight financial plan that is part of a large scheme. As projects are very cost intensive one of the main roles of project managers are to estimate total costs and ensure the budget is kept throughout the duration of the project. Libya is a developing country that has a growing construction industry, however, the management of construction projects frequently experiences challenges with time and cost restraints and this affects the overall performance of the project as well as the performance of the project managers. The main aim of this thesis is to investigate and evaluate the factors that impact project manager performance and their ability to complete and deliver projects successfully in Libya. This study will ascertain the role of project managers, the challenges that project managers in Libya frequently encounter the cause of time and cost overruns within construction projects and the main factors for successful construction projects. This research adopted both quantitative and qualitative research methods. The findings are based upon 300 structured questionnaires distributed to general, project managers working on construction sectors in Libya (Tripoli). Completed questionnaires received were 183. This is a response rate of 61%. The data was analyzed by using factor analysis (FA). A statistical analysis was used to confirm and addressed the issues of reliability and validity of the questionnaire survey as a measuring instrument. In addition structured interviews with qualified project managers were used to confirm that the data collected was truly reflective. Upon the data analysis from the questionnaire survey and structured interview that the project manager is the most important factor affecting the success of the project in construction industries Libya, furthermore project manager skills are important component that influence the performance of project manager. Proposed guideline has been adopted for implementation of balanced scorecard in Libya to help construction organisations improved their strategic management system. Finally, the conclusions, key findings, recommendations to industry, limitations of the study, and possible further work in research were discussed.