Abstract: This study was conducted to identify the critical causes and impacts of cost overruns on public sector construction projects in Port Harcourt metropolis. It further attempts to determine the measures that can be taken to minimize the impacts of cost overruns on public sector construction projects and to establish critical success factors for public sector construction projects in Port Harcourt metropolis. Structured questionnaires were used to determine the participants’ responses with respect to the identified factors from the reviewed literature. These respondents were mainly registered construction professionals working in Port Harcourt.