For about 10 years beginning in the mid 1990s, Northern Ireland had its own women's political party. The Northern Ireland Women's Coalition (NIWC) was created by members of the women's movement to achieve “equitable and effective political participation” for women. Despite being small, marginal and short-lived, the party increased access for women in nearly all the other political parties in the system. I connect the scholarship on social movements with that on political parties by examining the impact a social movement can have through the venue of its own political party. I argue three main points. First, the success of the NIWC means political parties may be an under-employed tactic in the repertoires of contention used by social movements. Second, the way the movement had an effect as a party is under-theorized in the literature on social movements because it requires consideration of party-system variables such as competition and issue-space. Third, as an identity-based movement, the women's movement in NI construed its goal of access differently than social-movement literature typically does. This under-utilized and under-theorized tactic of movement qua party delivered gains with the potential for long-term influence over policy and cultural values. In short, the movement-party may be an effective mechanism for changing the patterns of democratic representation of marginalized groups.