During World War I the building was used for Red Cross activities, but after that, until 1930, it was not used for anything at all. The effects of 20 years of neglect would have been disastrous except for the intervention of another Priestley descendent; in 1928 J. Priestley Button of Philadelphia sponsored repairs and repainting of the chapel.

In 1930, the AUA sent a representative to Northumberland to assess the possibility of reactivating the church but the report was negative. At that time there were only 3 Unitarians in town. The same year Mrs. Frances Forsyth, the last survivor of the Priestley family in Northumberland, died leaving a bequest of $1,000 for maintenance of the chapel. Despite the negative assessment, the AUA decided to try to revive interest in the chapel by engaging Rev. Robert S. Miller of Lancaster to preach a service. The results were encouraging enough to warrant turning the electricity back on and holding annual memorial services .

In 1939, it was decided to install pews to replace the caned-bottom chairs that had been used in the nave. The funds were provided by the interest earned on the Priestley family bequests and by the sale of 48 chairs at $1 apiece. The pews were built by a local carpenter, Fred Troxell, to match the original ones beside the pulpit.  Eight remaining chairs were stored in the cellar and sold in the mid-1990’s for somewhat more than $1 each.

Attendance was so impressive at the annual service that, in 1940, Rev. Miller agreed to try monthly services. Some improvements were made at that time, such as cementing the cellar floor, replastering the cracked ceiling, installing better lighting, and rebuilding and replacing the shutters for the stained glass windows. The monthly services were fairly well attended at first but with the onset of another world war attendance fell off and they were discontinued once again.