To anyone at all acquainted with the place which the Dutch Reformed Church in London has occupied during the centuries, it will not cause surprise to hear that I hesitated for a moment before accepting the invitation from its Council to relate the history of the Church on the occasion of its four hundredth anniversary. Not much time was left, and the material was voluminous. Only few church communities possess such a wealth of written documents bearing on their past history, or have been the centre to the same extent of so many varied activities. However, there were considerations on the other side, which made me decide to undertake the work. The extensive archives of the Church are well arranged and well preserved. The most important part, the voluminous correspondence, consisting mainly of letters addressed to the Church Council, has been made available, in a highly meritorious manner, by J.H. Hessels' publication: "Ec clesiae LondinoBatavae Archivum". Only a small part of the - often very detailed - minutes of the Council meetings has been published, but these pUblications by Dr. A. Kuyper and Dr. A.A. van Schelven cover two very important periods in the history of the Church. In addition, there are the pUblications of the Marnix Society, viz. Ruytinck's "Gheschiedenissen" (Hi story) and its sequels, and the Acta of the Colloquia of the Dutch church communities in England