Intraparty politics is a precursor to political parties’ policy proposals, manifestos, selected leaders and candidates, which often involves many actors and is regularly accompanied by tensions. This essay introduces the contents of a special issue devoted to the internal dynamics of political parties in Europe. We connect each contribution of the issue to three key aspects of intraparty research: (1) sources of information on internal party politics and methods of analysis, (2) how contemporary parties reconcile or otherwise address disagreements within the party and (3) the electoral and other ramifications of internal party tensions or divisions. Overall, the comparative case studies and cross-national comparisons across Western and Eastern Europe included in this issue show that considerations of intraparty dynamics advance scholarly research on alliances and coalitions, party organizations and party competition.