'Pugwash' is an international movement for peaceful cooperation between scientists, with special reference to the dangers of new methods of warfare. It takes its name from Pugwash in Nova Scotia, where the first conference was held in 1957.

Peierls played an active part in this, as in other movements aimed at international understanding; he also served on the Continuing Committee 1963-1974 and was its Chairman 1969-1974, and gave the annual Pugwash Conferences priority wherever possible over other engagements.

The folders preserve the order in which Peierls kept the documents and correspondence, though there is some overlap of contents.