In 1940 and 1941 more excavation was done in the basement of the church to make the Gifford Room, classrooms, and offices. The cost was $3,000. Most of the work was done by the men of the church and the Brotherhood Class. Painting and other renovations were also done at this time, as well.
Church membership increased rapidly. Between 1911 and 1943, town population increased 59% while church membership increased 164% In 1911 church membership was 283, by 1943 it was 747. In 1944 Old South was considered to be on of the stongest churches in the New England Conference. The church school was thoroughly deparmentalized with fifty-five officers and teachers and an enrollment of nearly 600, and an average attendance of 300. The Women's Society of Christian Service was flourishing with nearly 200 members, and the Brotherhood Class was stong and active.
In 1947 and 1948 the first floor of the parsh house was dug up and leveled off. The first floor was redesigned to provide space for religious education classes and church group meetings. The second floor had been converted to a gymnasium.
The Junior Choir was founded in 1945 by Marjorie Hills, and was directed by her for many years.
In 1941 the Women's Society of Christian Service (W.S.C.S.) was organized, uniting all the women's groups. It had 153 charter members.