Despite the widespread recognition of the relevance of intra-party democracy (IPD), there has been a lamentable scarcity of empirical data suitable for large-N cross-sectional comparative analysis. This has changed with the PPDB project. Against this background this chapter sheds some light on questions about whether and how IPD varies systematically by country and party level criteria. The empirical analysis shows that country-level factors are generally more important than party-level factors. Most importantly, the existence of a party law and levels of trust and affluence are associated with higher levels of IPD. However, we also find that smaller parties, in terms of membership size, are associated with higher levels of IPD. While our results must be interpreted with some caution we believe they constitute a first step towards re-framing the scholarly debate on IPD from what is normatively desirable to a discussion about causes and consequences of variations in IPD.