This article contributes to the debate about how we define the single woman by thinking about what makes someone ‘married’ as opposed to ‘not married’. It argues that understanding what marriage meant in a particular society can shed light on what it meant to live as a single person in that society, in this case, the society of fourteenth and fifteenth century England. It also argues that ‘the margins of marriage’, the grey areas produced by definitions of marriage, are also at the margins of singleness, thus adding the separated and the divorced to the never married and the widowed as those who might be considered as single. The article therefore discusses how the canon legal rules regarding marriage formation and dissolution actually blurred some of the differences between the single and the married, both in theory and in practice. From a discussion of provocative legal cases, heard before a variety of courts, it concludes that marital status can be seen as a performance that had to be acted out in order to be visible. To this end, it also considers the ambivalent evidence of married women sometimes claiming and sometimes denying femme sole status, of acting as if single and then acting married.