This paper uses as its departure point the framework of “transitional equality” that centers the socio-legal experience of shifting relational status. It uses as a key example the shift of hundreds of thousands of same-sex couples in the U.S. traversing the marital border through the nationwide availability of marriage. This concept provides a space to address inequalities that may arise during the process of legal relational transition. Movement across the status border of marriage, while bringing important legal protections, also reveal a variety of social and structural dynamics, influenced by economics, race, gender, age, and legal awareness, that shape experiences of equality. It also highlights transitions within the socio-legal institution of marriage, revealing boundaries between social norms and legal structure, pertaining to gender and other forms of equality. This paper connects insights in the U.S. context with recent legal change concerning marriage internationally.