This community service began in 1785 when a small congregation of Baptists gathered in the village of Washington, now known as South River. The group purchased property in 1799 from residents Thomas Robinson and Henry Obert and constructed a church in 1805. It was the only church in this area until 1851. The Old School Baptist Church is one of the few remaining satellite churches established by the First Baptist Church of Hightstown a the end of the eighteenth century.

The original front of the building was located on the east (river) side. It was a single story, three bay, clapboard sided facade with a central entrance. The interior spatial arrangement seems to have consisted of a single worship space.

In the middle of the nineteenth century, a major expansion and renovation was undertaken. The structure was expanded vertically to include a second story that accommodated a gallery level on the east, north, and west sides of the worship space. The portico, supported by four 20 foot tall columns, was added to the north side facing Main Street.

The early twentieth century brought a decline in parishioners and, beginning in 1920, the elders of the church began to sell off lots to raise capital, reducing the churchyard from one acre to one fifth of an acre. The church was sold to the First Free Public Library for $5000 in 1922. The library was dedicated on January 12, 1923.

Major improvments included new floors on both levels in 1926, windows and their trim and roofing replaced in 1927, and a restroom added.

In 1932, Anna (Emma) Martin, the last surviving member of the congregation, sold the last remaining church lot to the Library Association.

In 1936, an oil-fired central heating system was installed to replace the old stove. Due to termite damage, the floor, corner posts, foundation sills, and bottoms of some studs were replaced in 1950 and a false ceiling was installed to save heat.

The Library moved to a new building on Appleby Avenue in 1979, and the Borough Clerk moved his office into the empty Old School Baptist Church building. Part of the second floor was occupied by cable TV35, and the remaining space was used for storage for the Borough Clerk's office.

In 1991, due to some internal deterioriation, the large tree trunks encased within the portico columns were replaced with steel beams which were re-encased with the original cladding material.

Through the efforts of the South River Historical & Preservation Society, local residents, and the support of the Mayor and Council, the property was placed on the New Jersey Register of Historic Places on November 19, 1991, and on the National Register of Historic Places on January 7, 1992.

Upon the initiative of the South River Historical & Preservation Society, the Borough Council applied for a grant for restoration of the building which was badly in need of repairs. A grant in the amount of $210,230 in matching funds was approved in June 1995. The grant was funded by the Historic Preservation Bond Program and administered by the New Jersey Historic Trust.

The first floor of the restored building is used by the Borough for small meetings and by the South River Historical & Preservation Society for exhibits and meetings. The Historical Society uses the second floor as office and storage space.

The cemetery behind the museum hosts the work of famous American sculptor John Frazee, an urn in memory of his wife Jane. Of the approximately 75 markers that were inventoried in the cemetery in 1941, only 53 were still extant in 1993 when a second inventory was taken.

Plain in design and plan, the unornamented structure serves as a lasting reminder of the simplicity of the earlier Baptist congregation who built the meeting house.