This paper focuses on husbands'and wives' party political identifications in combination. There is a high level of party political homogamy in Great Britain (i.e. spouses tend to share the same party political identification). Statistical analyses show that levels of homogamy vary according to strength of party political identification, parental homogamy, age, and marital status. Levels of party political similarity are also shown to differ between marriage and other social relationships, and between first marriages and remarriages. Attitudes towards homogamy are shown to vary with age. The implications of these findings for theories relating to the origins of homogamy and to the consequences of heterogamy are considered. Broadly speaking, the findings indicate that party political homogamy is a consequence of demographic constraints, utility-maximizing choices, and responses to cultural norms.