This article examines comparatively the stances of Serbian and Croatian political parties on European integration in relation to their international affiliations. It specifically seeks to explore how and to what extent the European People’s Party (EPP) exerted influence on parties from these two countries. The article analyses the nature of these linkages in a systematic manner by employing the concept of direct and indirect transnational impact. The study argues that, in general, the EPP was not a crucial driving force behind party stances on the European Union (EU) and its direct impact was rather low. However, the EPP appears to have had a considerable indirect impact on parties that were at an early stage of ideological transformation towards becoming credible mainstream and pro-European parties, after a long legacy of Eurosceptic and nationalist politics. These parties strove to obtain European legitimacy by becoming members of the EPP and were, consequently, more willing to harmonise their positions with (potential) European partner. Moreover, ‘EU commitment’ of Serbian and Croatian applicants, closely scrutinised by the EPP, was primarily related to their affirmative positions on EU membership, rather than their stances on any particular model of European integration.