St. Mary's Home for Children opened its doors in 1877 as an orphanage within the Episcopal Diocese. Reverend Daniel Ingalls Odell was rector of St. Mary's Church in East Providence, Rhode Island when a couple in his parish died leaving two children. During the same winter another couple died leaving five children. Father Odell took them in and provided for their care. St. Mary's has always been a non-profit agency, committed to serving the changing needs of children and families.

In 1879, St. Mary's became an Incorporated Institution, under the name of St. Mary's Orphanage, governed by a Board of Trustees, with the Bishop of the Diocese as President.

By 1925, so many applications were being received that it became necessary to find larger quarters. In 1926, Mrs. Theodore Gibbs from Newport, contributed one hundred thousand dollars to St. Mary's Orphanage. Seven acres of land were purchased in North Providence for a new location. After fifty years in East Providence, Rhode Island, St. Mary's moved to its present site on Fruit Hill Avenue in North Providence. In 1928, the charter was revised to name the orphanage, "St. Mary's Home for Children."

Keeping up with the times and the needs of its clients, St. Mary's has added many services over the years. The facilities were extended in 1954, to include a separate residence for teenage girls, St. Martha's House. In the 1960s, St. Mary's began receiving requests to accept children who displayed behavioral problems both at home and in the community. St. Mary's psychiatric program which had been established in the 1950s proved to be invaluable.

The 1980's were a time of tremendous expansion and for St. Mary's. The George N. Hunt Campus School was established in 1982; developed for behaviorally disordered residential and day students who for various reasons have failed to succeed in public school. The Shepherd Program was established in 1985 in response to the growing need for therapeutic intervention for child victims. It is a specialized state-of-the-art, out-patient treatment program for child victims of sexual abuse, children with sexual behavior problems, juvenile sex offenders, and their families.

In the fall of 2004 St. Mary's added two new Acute Residential Treatment Services (ARTS) to its existing programs. The Jodie House and Harding House Programs provide short-term psychiatric hospital step-down services with complete diagnostic and assessment capabilities for girls and boys. In these staff-secure settings, children benefit from daily clinical interventions, a structured therapeutic environment, academic and recreational programming and intensive psychiatric and nursing services.

Over the years, St. Mary's has evolved into Rhode Island's largest, most comprehensive treatment facility for abused and neglected boys and girls. Children cared for in both the Home's residential program located in North Providence, and the outpatient program located in the Sophia Little Building in Cranston, Rhode Island. St. Mary's Home for Children is governed by a Board of Directors. While it still receives some support from the Episcopal Diocese, St. Mary's is a non-sectarian organization working with children from diverse religious and ethnic backgrounds.