Collection includes about 8,000 vols. donated by Isaiah Thomas, founder of the Society. The catalogue is "almost wholly the work of the late lamented librarian, Christopher C. Baldwin ... completed and brought up to the present date by ... Maturin L. Fisher."

The collection of English books printed before 1801 in the University Library of the Vrije Universiteit at Amsterdam is one of the largest collections of such books outside the English-speaking world, and by far the largest in the Netherlands. The collection numbers 5,600 titles and covers all subjects, but is especially concentrated on (reformed) protestantism in Great Britain, the Netherlands and America, and the exchange of ideas between these countries. The collection of which the existence is practically unknown, contains many rare items from the 16th to the 18th century. It covers the periods of the well-known and widely used bibliographies of English printed books (STC, Wing, and ESTC); in a large number of cases the catalogue entries correct or supplement these bibliographies. The catalogue is aimed both at a general public of bibliographers, literary and book- historians working with books from the STC, Wing and ESTC periods, and at researchers in the Netherlands, Great Britain and elsewhere specialised in church history and the manifold historical and cultural relations between the British Isles and the Low Countries.

In this 1957 work, Dr Cragg has written a detailed history of Puritanism in the Commonweatlth.