In the conventional approach of construction projects, the design and construction processes are notrnimplemented in integrated approach. The design work often begins with the clientâ€™s needrnidentification then after discussion and agreement the architect and engineers prepare the design withrnthe available resources and constraints. After the completion of the architectural and the engineeringrndesigns the procurement and construction will continue respectively. In the process of the design andrnconstruction processes are not integrated. This lack of integration between the two processes is therncause of many problems like cost overrun, delay, less quality, incompatible with the availablerntechnology and so on, in general lack of constructability of a project.rnProject delivery methods have the major impact on the integration of the design and constructionrnprocess. According to literatures DB is a better project delivery method with regard to integration ofrndesign and construction phases and constructability issues over DBB. The main objective of thisrnstudy is to review and assess the theory and actual practice of the project delivery methods withrnrespect to the integration of design and construction and the effect of constructability in publicrnbuilding projects in Addis Ababa.rnIn order to realize the objectives, case study of three selected public building projects in Addis Ababarnis reviewed. In contrary to the literatures, the results of the case study indicated that, in publicrnprojects, the DB project delivery method is not practiced in proper manner like; the right type ofrncondition of contract is not implemented , the design and construction processes are not integratedrnand others. Accordingly in the actual case of public buildings in Addis Ababa DB have manyrnproblems, even higher than DBB projects with weak quality control, too much variation, timernoverrun, and dispute between contractual parties. In addition the concept of constructability is notrnpracticed in the studied projects of either in the DBB or DB public building projects.rnKeywords: - Project Delivery Methods, Integration of Design and Construction, Constructability