This master thesis summarizes contemporary theories on secularization processes in the Western world, and compares these with the example of Sweden, which by many scholars is considered to be the most secularized country in the Western world. I do this by dividing the most influential theorists in five different groups. In each group I explain how the theorists formulate and motivate their positions. These groups are: 1) The secularization paradigm, where secularization always accompanies modernization. (Therorists: Steve Bruce and Peter Berger (in the 1960s) 2) The paradigm basically accepted, but revised to depend on existential security, rather than modernisation as such. (Pippa Norris and Ronald Inglehart) 3) Religion returned in the public sphere. (José Casanova) 4) The paradigm completely revised. (Peter Berger (after 1990), David Martin, Charles Taylor) 5) The post-secular society. (Jürgen Habermas, plus others) After this theoretical overview I compile empirical studies on the Swedish example, mainly using the scholars Eva Hamberg and Magnus Hagevi. Apart from these, I mainly use material from Sverigeräkningen – a study of all church attendances in Sweden at one weekend in 1999; plus recurrent studies from the SOM Institute at Gothenburg University as well as from World Values Survey. This essay concludes that there is good reason to think that the secularization paradigm is in need of revising. However, there still seems to be some truth in all these theoretical models, essentially because they do not necessarily contradict each other, as much as they deal with the issue from slightly different perspectives. The empirical studies of Sweden indicate that our country is indeed highly secularized. The reasons for this may be found partly in all of the theoretical models used in this essay. It is also argued that there may be good explanatory power in the market model, where secularization comes not only due to lack in demand, but also to a weakened supply of religion.