This article explores the treatment of same-sex spouses and same-sex registered partners in European private international law (PIL). The discussion encompasses national PIL frameworks in EU and non-EU countries, as well as EU PIL rules. The aim is to identify legal obstacles facing mobile same-sex couples as they move around Europe, and to highlight the inadequacies and anomalies in the existing law. It is argued that the extension of the PIL rules traditionally applied to different-sex marriage may be problematic for same-sex couples. The article also seeks to analyze the PIL responses to domestic laws in transition (in adopting registered partnership – and in progressing from registered partnership to marriage equality). The complex implications (and interactions) of EU PIL instruments are also scrutinised. The discussion concludes with an assessment of how existing problems may be resolved (with a particular focus on human rights jurisprudence and the EU free movement policy).