The sanctuary of our church was built in 1892 and is the oldest Unitarian Church in New Jersey. The architect was O.M. Teale, and the design featured rusticated stone, multiple windows, turrets, and towers placed asymmetrically.

In 1929 the internationally known Norwegian artist Jonas Lie (1880-1940) painted a mural in an arched space above the pulpit. The mural is entitled “I will lift up mine eyes unto the hills”.

In 1947 the Robinson Window was installed. This large stained-glass window was designed under the direction of Cateau DeLeeuw and crafted by Oliver Smith of Philadelphia. It faces Park Avenue and is named in memory of the Reverend Alson H. Robinson.

In response to a growing congregation, a connecting Parish Hall was added to the church in 1925. It was designed by Josiah T. Tubby, an architect and one of the society’s members. The Parish Hall features a large room with a high ceiling, a stage, offices and kitchen. For a while the Parish Hall was used as a meeting place for a Public Forum. Many well known speakers were heard. Amateur theatricals were held and continue today.

In 1958 another large addition was made to the church, the Stevens Wing, consisting of two floors of classrooms and meeting rooms. This addition extends northwesterly from the Parish Hall. At its farthest end is the Stevens Room, named after prominent member Helen Coburn Stevens. It opens out into the yard and a Memorial Garden.

The First Unitarian Society of Plainfield, N.J. was incorporated August 26, 1889 and, some three years later, the Reverend Hobert Clark christened the building All Souls's Church on May 11, 1892. As of December 11, 2009 All Soul's Church has been listed on the National Register of Historic Places. The reference number for All Souls is 09001078.