Over the years, smaller bodies such as the Scottish Protestant Alliance, the Scottish Women's Protestant Union and - much later - the Protestant Institute of Scotland have been incorporated into the Society. The last of these was a major step in the development of the Society.
The Protestant Institute was found in 1860, one the 300th anniversary of the Scottish Reformation. It owned the property at 17 George IV Bridge, Edinburgh, which housed the Institute, a teaching centre and the offices of the Scottish Reformation Society up until recently.
Discussions took place over several years, in the early 1960s. This culminated in an agreement in 1964 to incorporate the two bodies under the style and title of the Scottish Reformation Society. All assets and property of the Protestant Institute were transferred into the new, combined body.
Opportunity was taken at this time to examine the Constitution of both of the former bodies. In the wake of this, a new Constitution was written and approved by the Committee and the Annual General Meeting of the Society held in 1965. A further update of the Constitution has taken place in February 28th, 1992