Typically, public building construction projects face cash flow problems due to several reasons. Prior studies on cash flow problems show that the problem arises from delayed payment of owners, poor cash flow analysis, lack of financial support, and poor budgetary control. However, there are limited studies that pinpoint the challenges and root causes in the Ethiopian construction industry. This thesis investigates the causes and impacts of cash flow problem and measures to address the problem. This study followed an inductive research approach. To achieve the study objective, questionnaires were distributed by applying simple random sampling; semi-structured interviews were conducted through purposive selection; case study analysis was carried out on completed projects. The results from the questionnaire were analyzed using quantitative data analysis. The case study and interview data were analyzed using qualitative data analysis. The research results showed that delayed payment from a client; poor estimation and underpricing of contractors; contractor use of project budget for other commitments; subcontractors’ presence in non-profitable tenders; market inflation; and error in design and detailing were major causes of cash flow problem. The results also showed that the failure of contractors to pay their duties and delay in project completion was the most significant impacts of cash flow problem. Mitigation measures such as examination of under-billing and over-billing, subcontracting, and minimizing cash flow problems by applying resource optimization are potential solutions. Thereafter, the researcher suggested a conceptual framework for improving the contractor's cash flow. This research concludes that delayed payment is the major cause of cash flow problem, while unable to pay duties is the major impact of cash flow problem; while monitoring underbilling and overbilling is the solution to solve cash flow problems. The findings of this research could help in improving cash flow of construction projects.