While it is commonly assumed that parliamentary opposition is on the wane in Western democracies, we argue that evidence supporting this established proposition is lacking. Therefore, drawing on unique data from the Swedish parliament (the Riksdag), between 1970 and 2014, this article breaks new ground by systematically testing the ‘waning–of–opposition thesis’. First, we explore patterns of cross-partisan cooperation by gauging the extent to which governments seek to accommodate the position of the opposition. Second, we tap into the degree of partisan conflict over time by mapping the degree to which the opposition politicises and rejects government policies. Our findings directly contradict the waning–of–opposition thesis. In contrast to theoretical expectations, including the influential ‘cartel party thesis’, the article finds that partisan struggles in general have intensified significantly over time. Therefore, the article casts a serious shadow of doubt over the influential idea that parliamentary opposition is waning.