Wright felt personally invested in this church, which took five years to build. His parents were among the earliest First Unitarian Society members, and Wright officially joined the organization in 1938. Members served as construction volunteers, hauling more than 1,000 tons of limestone to the site from a quarry 30 miles away. The design of the building is governed by a diamond module. The form is evident in the incised pattern in the concrete floor, the shape of the auditorium and hearth room, the zigzag interior wall of the loggia, and the stone piers and planters. The auditorium, with its soaring ceiling and glass prow, in combination with the adjacent hearth room, can accommodate 340 people.