This article analyses the conditions under which political parties pay attention to labour issues. It compares the dominant partisan perspective, which proposes that attention to issues is shaped by party competition, to an interest group perspective, which proposes that strong interest groups, in particular when their power is institutionalized in corporatist systems, can force parties to pay attention to their issue. We use the Comparative Agenda Project data set of election manifestos to examine these patterns in seven West European countries and corroborate our findings in the Comparative Manifesto Project data set for 25 countries. The evidence supports the interest group perspective over the partisan perspective. This shows that the study of party attention to issues should not isolate party competition from the influence of other political actors.