The term 'unpaid market labor' refers to the direct contributions of unpaid family members to market work that officially belongs to another member of the household. Thus one individual may be construed legally as an owner or entrepreneur, but relatives may help out informally with business operations. Likewise, in corporate or public-service settings, certain employees rely on the unpaid help of an executive spouse or political wife. This paper argues that unpaid market labor is conceptually distinct from both paid work and unpaid domestic labor. Legal cases from Canada are used to illustrate the policy implications of this insight and how dichotomous thinking about the market and the family obscures this kind of work. The article discusses insights and challenges for feminist political economy in theorizing unpaid market labor.