Different actors are important during transition from authoritarian rule and democratization, e.g. state institutions, political parties, non-governmental organizations, trade unions, the business sector, and the media. This comparative study looks at the leading political parties in Egypt and Tunisia, the Freedom and Justice Party and the Ennahda Party, and their role during the transitions that started with the 2011 Arab spring revolutions. These parties have certain common features as they are Islamist in their origin and orientation. Focus here is on the roles that they played in central processes during the transition, such as e.g. elections and constitution writing. Whereas Tunisia after the 2011 revolution continued on the road towards democracy, Egypt experienced a second revolution, or rather a coup d´état, which sent the country back to authoritarian rule. In 2016, Tunisia was declared by Freedom House to be the first "Free" (democratic) Arab state since Lebanon lost that status with the outbreak of the civil war in 1975. Egypt, meanwhile, is assessed as being more authoritarian and less free than it was during the Mubarak regime prior to 2011. The purpose of this study is to examine if – and if so, how – the actions and behavior of these political parties and their leaders contributed to the different outcomes of these transitions.