Though it has had a women’s movement for decades, for about 10 years beginning in the mid 1990s, Northern Ireland also had its own women’s party. The Northern Ireland Women’s Coalition (NIWC) was created in 1996 by a small group of Catholic and Protestant women in Northern Ireland who aimed to achieve ''equitable and effective political participation'' for women. Despite being small, marginal and short-lived, the party left its mark on the political system in NI, particularly in promoting women’s descriptive and substantive representation in nearly all the other political parties in the system. Like the women’s parties in Iceland in the 1980s and Israel before that, the NIWC put “gender politics on the political map for the first time” (Levin 1999, p. 48). When the NI women’s movement seized the new political opportunities presented by the peace process to change their repertoire and constitute themselves as a party, they were able to deliver a few concrete policy changes but even more importantly, they pressured the other parties to grant women access to the political process to a degree never before achieved in NI. Yet, the mechanisms of this process and the potential it holds for advancing women’s interests as well as those of other underrepresented groups is almost entirely ignored in the social movement literature. This paper considers the evolution of the NIWC and the impact the women’s movement had in NI through the venue of the political party. It breaks new ground in the social movement literature by considering how a party can function as the tactic of contention chosen by a movement. I argue three main points. First, the party advanced the movement’s interest far more than was possible through a continuation of protest or outsider activities and may thus 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 political party system variables such as party competition and issue-space, which are not typically included in scholarship on the outcomes of social movements. Third, this mechanism through which the women’s movement in NI succeeded pivoted around its goals of access, which it construed differently than the social movement literature does. Access for the women’s movement in NI meant increasing the descriptive and substantive representation of women in each of the political parties in the system at large. To achieve this, they formed their own political party to blackmail the other parties into granting women in their own parties access as candidates, representatives and leaders. The pressure the party placed on the other parties also forced them to change their approach to women’s substantive representation, including giving greater attention to women’s issues in their party platforms. This under-utilized and under-theorized tactic delivered gains with the potential for long-term influence over policy and cultural values.