The interior of the Old Adobe Mission is simple, as one would expect of a church built by volunteer Mexican laborers who were not construction workers by trade. A local businessman, Robert Evans, who owned the Jokake Inn, helped the Mexican immigrants with their church project.
Evans owned a construction company and he designed the building and loaned foremen to supervise the construction after their work hours. The priest for the parish obtained a gift of $1,000 from the Extension Society of Chicago to pay for the roof, which is made of heavy timbers that are connected to buttresses on the outside to support their weight.
The Extension Society was given the naming rights in exchange for their donation, and at their request the official name of the Mission is Our Lady of Perpetual Help.