Studies of post-conflict peacebuilding have flourished in recent decades. Most, however, focus on cases of externally led peacebuilding in fragile states with weak state institutions and inadequate national funding. By making a case study of peacebuilding in Aceh, Indonesia, this thesis contributes to the literature by examining state-led peacebuilding in a regional power with working bureaucracy and an ample national budget to finance peacebuilding programmes. Given that the peace in Aceh has lasted 13 years without major violence or breaches of the agreement, this thesis also investigates peacebuilding in the normalisation phase. This study is conducted through two phases of field research in three areas in Aceh, supported by extensive secondary data collection.

Five hypotheses are presented in this thesis. The first is that a peace agreement which addresses grievances will contribute to the durable peacebuilding process in middle-income countries with relatively strong governments, like Indonesia. Second, to secure sustainable post-conflict peacebuilding, a peace agreement should be enacted in national and local law. Third, participation aspects of peacebuilding will contribute to unification, recognition of identity, and legitimacy to address the underlying grievance. Fourth, institution-building will increase legitimacy, secure resources, and stabilise the conditions for lasting peace. Finally, in a country where the bureaucracy, state institutions and national identity have been relatively strong and settled, like Indonesia, state-led peacebuilding that combines participation and institution-building contributes to a durable post-conflict peacebuilding process.

The peace-building process in Aceh is firstly analysed by employing the concept of multiple grievances in politics, in the economy, around identity, and in human rights-justice, as the underlying factors of conflict. It is then followed by the analysis of various peace agreements and their subsequent regulations at the national and local levels in Aceh to test the proposed hypothesis that a peace agreement which addresses grievances and is enacted in national and local law will contribute to the durable peacebuilding process in a strong middle-income country like Indonesia. This thesis found that MoU Helsinki has addressed the grievances sufficiently and that the MoU has also been translated well into subsequent regulations at the national and local levels to maintain peace in Aceh. However, this thesis also reveals that grievance-alleviation through regulation in the subject of human rights and justice is halted at the national level but emerging at the local level through the promulgation of local law on the Aceh Truth and Reconciliation Commission.

Rather than applying specific peacebuilding approaches such as liberal, illiberal, or hybrid peace, this thesis observes the implementation of the peacebuilding process in Aceh through the methods of participation and institution-building. This thesis discovered that the combination of participation and institution-building had contributed significantly to the durability of peacebuilding. It occurs because the institution-building that is manifested through the establishment of reconstruction and reintegration agencies as well as customary and religious institutions helped to secure resources and strengthened the legitimacy of former combatants and religious group in Aceh. Meanwhile, participation in some aspects of peacebuilding, especially in electoral politics, has successfully alleviated grievances of political centrality during the conflict period.

Another important finding is when approaching the normalisation process, there is an indication of a stronger link between Aceh local government, dominated by ex-insurgents and the central government, to achieve political goals at both provincial and national levels. A patron-client network within he circle of a former insurgent group in the transition phase is sustained during the normalisation era through the utilisation of a special autonomy fund as a peace dividend. Regarding participation, this thesis further demonstrates the achievement of some bottom-up participation from the community and civil society in establishing the Aceh Truth and Reconciliation Commission in the normalisation phase.

This thesis illuminates the trend of elite-based peacebuilding in post-conflict Aceh. Sustainable peace must be carefully managed to avoid the domination of a powerful group in Aceh. The prolonged supremacy of one group over another will potentially repeat the grievances that triggered the conflict in Aceh many years ago. In addition to durability, peacebuilding in Aceh must also be based on inclusivity.