As the Hershey community expanded, Derry Church continued to play an important part in town events. In 1915 Derry Church celebrated Arbor Day by planting 50 trees. It was a major event, not just for Derry but for the entire town of Hershey. One of the trees from that 1915 planting is still part of the church grounds. A Scarlet Oak stands near the rear entrance to the Sanctuary. 

     In 1929 Milton Hershey once again came to the aid of Derry Church. The Session House was known to be the oldest structure in Dauphin County. The church was proud of the Session House and the role it had played in its history. At the time, the church was concerned about the preservation of the building. One day Mr. Hershey and Harry Erdman, manager of the Hershey Nursery, came to the church grounds to look at some of the trees. Reverend Robert Taylor came to greet them. He asked Milton for a contribution to preserve the Session House. Hershey replied that he had seen something in France that might work to preserve the structure and told Reverend Taylor that he would take care of it. Milton Hershey is the man behind the glass structure, constructed to preserve the historical Session House.

     A few years later, in 1935, Derry Church began a construction project and as construction was nearing completion, Milton Hershey gifted each of the Hershey community’s five churches $20,000 (Derry Presbyterian, Hershey First Methodist, Spring Creek Church of the Brethren, St. Joan of Arc, and Holy Trinity Lutheran). The gift helped many churches cover financial shortfalls resulting from the Great Depression. Derry Church used Mr. Hershey’s unexpected gift to expand the construction project. Hershey's commitment to the community he established extended to churches that served the residents and maintained a centuries-old historical part of Derry.