The Companion focuses on the major theories, concepts, and conclusions that define the field, analyzing the similarities and differences between political units. Additionally, the Companion outlines those comparativists who have influenced the field in significant ways, and politicians whose administrations have shaped the evaluation of contrasting governments.

Drawing on the depth and breadth of content from the Oxford Companion to Politics of the World, the Oxford Companion to Comparative Politics contains nearly 200 revised and updated articles from this foundational set in addition to over 100 new entries, which thoroughly examine the field.

New entries cover such topics as failed states, Grand Strategies, and Soft Power; important updates include such countries as China and Afghanistan and issues like Capital Punishment, Gender and Politics, and Totalitarianism. In addition to individual entries, 25 interpretive essays are included, authored by notable figures in the field who have analyzed the discipline, its issues and accomplishments. Collectively, entries promote deeper understanding of a field that is often elusive to non-specialists.