The synod appointed by the Long Parliament in 1643 to reform the English Church. It consisted of 30 lay assessors and 121 clergymen of widely different views; when the Solemn League and Covenant was adopted it was increased by five clerical and three lay Commissioners from Scotland.
The Assembly began by revising the Thirty-Nine Articles, but with the appearance of the Solemn League and Covenant it turned to the production of a new formula, the Westminster Confession (q.v.). It also prepared the Directory of Public Worship (q.v.) and the two Westminster Catechisms (q.v.). Although only partially and temporarily accepted in England, these documents came into general use throughout the Presbyterian world.