A delay in construction projects is a global phenomenon that causes significant losses forrnresources. Delays and cost overrun are common problems in building construction projects due tornseveral factors, but their frequency of occurrence and degree of severity vary significantly. As arnunique nature of construction projects, completion time delay can be minimized when the potentialrncauses and effects are properly identified. rnrnThe main objective of this research is to identify the major causes and effects of delay in thernconstruction of Addis Ababa 40/60 housing project. A total of 99 respondents participated thatrnrepresents client, consultants and contractors in the survey and 20 major causes of delay werernidentified based on the relative importance index from a list of 70 causes of delay. rnrnThe research finding indicates that late delivery of materials by the client, difficulties in financingrnproject by contractors, improper contractor selection, slow decision making by the client andrnobsolete technology used by contractors were some of the most dominant delay factors. For therntop 20 delay factors a number of another root causes are identified for their occurrence. Therncumulative effects of those varieties of causes for the incidence of major delay factors contributedrna great role on the project timely completion failure and the project is delayed by more than 150%.rnFrom the investigated major causes of delay, client sourced and contractor sourced delay factorsrnwere the major bottlenecks of progress.rnrnDue to the acute delay of the project, 24 serious effects were also identified and the result showsrnthat cost-overrun, time-overrun, increase unemployment rate, client loses time value of money, therngovernment mistrusted by the people and reduce the quality of construction were some of the mostrnsevere effects of delay. To minimize those severe delay problems and inevitable outcomes somernrecommendations are forwarded.