Many post-conflict societies, even those which have been free from active conflict for decades, continue to be heavily divided along the same lines on which the conflict was once fought. While active conflict might be a distant memory, the legacy of conflict ensures the group identities which either caused or were borne out of the conflict remain strong. Achieving a situation where a society truly lets go of the anger and resentment that fuels its divisions has proven to be an allusive prospect, however, it’s a goal many post-conflict states continue to reach for. The effort a state uses to try to deconstruct these potentially harmful social identities and to deal with the conflict-related grievances which strengthen them can be loosely understood as post-transitional justice. Part of the reason why effective reconciliation has proven so difficult is that post-transitional justice typically requires societies to reopen old wounds and publicly address challenging memories. Thus, in the context of divided post-conflict societies, post-transitional justice, if not properly implemented, can itself be a divisive procedure and one that risks heightening tensions rather than reducing them. Despite this clear risk, little research has been conducted to understand what factors are likely to make the difficult process of introducing post-transitional justice more or less successful. This thesis addresses this research gap. It uses a social identity approach to examine how socio-political context influences group identification and inter-group behaviour in divided societies and how these behaviours subsequently impact how those groups perceive post-transitional justice mechanisms. This thesis draws on the timely case of Northern Ireland, which is in the process of introducing a wide-reaching post-transitional justice mechanism at a time when the socio-political context has been markedly challenged by Brexit and other socio-political events. Through a mixed methods approach which used both questionnaires and key informant interviews, this thesis demonstrates how the recent socio-political context in Northern Ireland has significantly heightened nationalist and unionist identification with their groups and has concurrently heightened tensions between the two groups. This thesis shows how this environment has subsequently made these groups less likely to accept the terms of the post-transitional justice mechanism, thus limiting its ability to reach its goal of creating an enabling environment for reconciliation, trust, and peacebuilding.