Typologies of oppositions created over the years have often taken into account systemic factors thought to affect the main characteristics of the opposition in each parliamentary democracy, including electoral and party systems, strength and composition of the executives, and the rules of the parliamentary game. This research aims to take a step further in order to better understand the influence those variables have on the concrete performance of oppositions in parliaments today by separating the analysis into two distinct levels: an internal level, focusing on relationships among opposition actors and in particular on their organizational cohesion, and an external level, focusing on the relationship between government and opposition. Two very different cases as regards the main systemic variables taken into consideration will be investigated: Italy and the United Kingdom.