The concept of a political opportunity structure contributes to the analysis of the behaviour of political actors and is one of the current central topics that has importance for political systems at the regional and international levels, as well as for political and social scientific research centres. This study falls within the range of studies on ideological movements and political parties, and the political variables that affect the political system and these movements which lead them to adapt their ideology, by changing their position – from one of rejection to one of acceptance – with regard to participation in parliamentary elections. To achieve their aim of getting into power, ideological movements and political parties can adapt to political changes, influence the structure of political opportunities and exploit ones available to them. This study focuses on the analysis of factors that led to the change in the position of Hamas with regard to democratic practice, from boycotting the first parliamentary elections in 1996 to actively participating in the 2006 elections. It discusses a number of factors: first, the internal organizational factors of the movement; second, the political variables in the Palestinian arena; and third, the internal factors related to the ruling party (Fatah). In light of this, the study principally aims at providing an objective view on the position of Hamas with regard to its political and democratic practice prior to its participation in the Palestinian political system and beyond, using the concept of political opportunities structure. Given that the movement was restricted by its ideology and governed by the political changes that had taken place in the Palestinian political system, it was forced to adapt to the new circumstances that followed the Oslo Treaty by changing its position from opposition and rejection to political participation.