In this paper we look at the ability of parties to influence their own voters’ issue positions in seven advanced Western democracies. We use evidence from a comparative experimental CAWI survey we have conducted in Canada, Denmark, France, Germany, Italy, the UK, and the US. Respondents are asked to report their position about a possible military intervention in a foreign country to stop a genocide. The treatment consists of a cue about the position on the issue of one of the major parties, with party positions randomly assigned to favoring or opposing the military intervention. We first estimate and compare ATEs across various countries. In particular, we assess the differences in support for the intervention based on the cues of a party to which the respondent has some kind of previously measured affinity. Furthermore, we are also able to disentangle the different effects of favorable and contrary partisan cue treatment. Finally, we use a multi-level regression model in order to assess how treatment effects vary with party characteristics (such as ideological placement, electoral size, and age).