This doctoral dissertation examines the process of preparing, elaborating and implementing Belgrade’s 1923-24 General Urban Plan. The impact of design proposals from the 1921-1922 international competition on the content and concept of the General Plan is analyzed and a comparison is made between the General Plan’s ideas and its achieved results, by taking a look at what hindered the Plan from being implemented. As the capital of the Kingdom of Yugoslavia, Belgrade’s urban planning and development in the period between the two world wars are considered within the context of social and economic circumstances in the newly-formed state.