Originating from discussions about the reasons for, and regional variations behind, the remarkable rise in cohabitation that started in the 1970s – a rise that continues to this day – this book explores the main stimuli behind cohabitation. The variation in levels of cohabitation cannot be explained solely by regional differences, religious affiliation, nationality, levels of education, or by the varying rate in which contraceptive measures spread across Europe. The book also focuses on the ways in which cohabitants are legitimized or rejected by certain communities.