Few existing datasets on parties and interest groups include data from both sides and a wide variety of interest groups and parties. We contribute to filling this gap by making several interconnected new datasets publicly available. The Party-Interest Group Relationships in Contemporary Democracies (PAIRDEM) datasets include cross-national data from three different surveys of (1) central party organizations, (2) legislative party groups, and (3) interest groups. A fourth dataset based on coding of party statutes and party finance data was established together with the Political Party Database. The datasets contain novel indicators on party-group relationships in up to 21 mature democracies. In this research note, we first present the main content of the datasets and the research design. Second, we present descriptive statistics documenting the extent of organizational ties between parties and groups in contemporary democracies. Third, we illustrate more advanced usage through a simple application.