This series consists of the manuscript letter books kept by the first three secretaries of the Society. Vols. 1-6 contain only in-letters; vols. 7-26 contain both in- and out-letters. The letters and papers are from and to the missionaries appointed by the SPG to the American colonies and also from the colonial governors, private persons and churchwardens there. In addition there are a few items from churches in Europe.The letters are arranged chronologically, but with some overlapping of dates as inland letters were copied into the books long before those of the same date coming from overseas. A few items are in Latin or French, with English translation. A list of letters in number order appears at end of most volumes, detailing sender and addressee.These letter books are of considerable importance, as the majority of the originals from which the letters were copied are no longer extant.