This data collection comprises primary research materials gathered for a PhD thesis that examines the pivotal role of mediators in facilitating the alignment of negotiating parties' perspectives during peace negotiations to end civil wars. Centred on the case study of the UN-mediated El Salvador peace negotiations from 1989 to 1992, the dataset includes in-depth transcripts from interviews with 18 individuals who played direct roles or were closely connected to these negotiations. Additionally, the collection encompasses a curated selection of relevant documents from the peace negotiations, sourced from the United Nations archives in New York and various collections in El Salvador. These materials offer invaluable insights into the dynamics of the El Salvador peace process, highlighting the complexities and strategic considerations involved in mediation efforts to resolve civil conflicts. The interviews provide unique, firsthand perspectives on the negotiation process, mediator strategies, and the challenges and successes encountered. The documentary evidence from the UN and Salvadoran collections adds a rich contextual layer, enabling a comprehensive analysis of the negotiation and mediation processes. Intended to support the thesis's exploration of mediation as a framing process, this dataset not only contributes to the academic understanding of peace negotiations but also serves as a practical resource for mediators and scholars interested in conflict resolution.

Interviewees were identified via secondary sources and snowballing. The semi-structured interviews (in both Spanish and English) were recorded and transcribed with the assistance of automatic transcription software. Documents from the UN archives were identified with the help of finding aids, photographed and converted into pdfs using a smart phone.