Livia Plaks was a co-founder of the Princeton-based Project on Ethnic Relations (PER) and served as executive director. This collection includes publications, correspondence, subject files and photographs created by Plaks relating to the PER.

The Project on Ethnic Relations (PER) was a not-for-profit organization based in Princeton, NJ concerned with the course of interethnic conflicts during the post-communist transitions in Central and Eastern Europe, Russia and former Soviet Union, and the Balkans following 1989 and extending into the 21st century. The collection consists of paper and digital reports and records of consultations, meetings, roundtables (and discussions and preparations for roundtables), and correspondence with leaders of political parties and representatives of governments and international organizations.