Partnership is important in terms of many social, economic and demographic characteristics, such as household composition or the provision of care at older ages. The majority of demographic and sociological analysis examines people as separate units. However, when exploring partnership behaviour it is important to go beyond this and examine both of the partners as well as the interaction between their characteristics. Age appears in most analyses of partnership behaviour, but often the ages of partners are not compared. Variations in age differences for partnership formation and dissolution may be of interest in themselves in understanding partnership change, but age difference effects may be relevant to the interpretation of any other statistics involving age and partnership status.