Following are the reasons of rise of Behaviouralism: 

1. Dissatisfaction with traditional study methods: 

Political thinkers were dissatisfied with the study method and the outcomes of traditional approach by 20th century. The main reason was that the real picture of political life could not be obtained through the traditional approach.

Those were not given any importance in government’s policy-making. Traditional approach lacked realistic study. Apart from this, this method was unable to explain the reasons of development and popularity of Fascism, Nazism, Racism and Totalitarian ideologies.

2. Effect of Second World War: 

The happenings during Second World War inspired the political thinkers for new researches and concepts. This became a common belief among political thinkers that it was necesarry to concentrate on political organizations and on the behaviour of persons working there,, rather than institutions and their organizations, to understand completely the complexities of political life.

3. Inspiration from various social sciences: 

Scientific study methods and realistic approach had already been used in other social sciences. So inspired by them, Political Science also started using scientific and new methods of study.

4. Use of New Study Methods: 

Increasing use of new methods, techniques, instruments, research methods, statistical approaches, etc. made study of Political. Science more realistic and helped behaviouralism to grow.