In the spring of 1855, a group of Irish immigrants settled in the town of Pleasant Valley and established what was to be known as the Hawkins settlement. These immigrants brought with them a deep faith and loyalty to the Catholic church. They had originally met in Connecticut and then again in Dane County before traveling to Pleasant Valley. The pastoral needs of the parish in Pleasant Valley were met by the pastors of the Seat of St Croix County. From Hudson, they would make monthly ministry travels by horseback and later by train. On the occasion of a visit by a priest, people would assemble at a home, which was called a station. There the Eucharist would be offered and other sacraments administered. The missionary would stay a short time to give religious instruction as well.
In 1876, the first Catholic church was built in Hammond, on the corner just north of the present parking lot. People coming to mass could tie their horses at the horse shed that was north of the church. The first rectory was constructed between the 1880's and 1900. The first recorded baptism was that of Charles Francis Lauder on Dec. 8, 1876. The first recorded burial, that of Anna Clelland, took place on March 15, 1878. Maria O'Brien and James Collins celebrated the first recorded marriage on March 5, 1879. During the twelve years of service to the parish, Fr. William White (1880-1892) baptized 582 people and officiated 67 marriages. On Sunday, Nov. 6, 1882, 112 people were confirmed at Immaculate Conception. Priests that followed included: Fr. James Nevins (1892), Fr. L.J. Fitzgerald (1892-1896), and Fr. B.P. Connolly (1896-1902). During Fr. Connolly's pastorate, the parish of St. Bridget's in Wilson was attached. On Dec. 12, 1889, the church in Hammond was incorporated as "The Catholic Congregation of St. Mary's Immaculate Conception." The parish belonged to the Diocese of La Crosse until May 3, 1905, when the Diocese of Superior was established by Pope Pius X.
From 1903 – 1914 Fr. H.F. Duffy was pastor of St. Mary’s Church. During this time the church moved from the north side of the old rectory to the south side. A full basement was constructed and two coal furnaces replaced wood stoves. Fr. Patrick J. Cunningham became the pastor in 1914 and served until 1947. New side altars were donated to the parish, one in honor of the Blessed Virgin (donated by the Altar Society) and one in honor of the Sacred Heart (donated by six women of the church). In 1946, Fr. Jerome Mee came to the parish. After the church burned down on Dec. 15, 1948, Fr. Mee supervised building the new church. Services were held at the community hall during construction.
The present church was completed in 1949 and dedicated on June 22, 1950 by Bishop Albert G. Meyer. Fr. Mee served the parish for 25 years, until 1971. On Sept 28, 1971, Fr. Joseph Canfield became pastor and helped with planning the new rectory and religious education center. On July 14, 1976, Fr. Dennis Dhooge was appointed pastor. He was involved in constructing the religious education facilities and installing the new altar in the cemetery. Fr. Gerald Harris served as temporary administrator of the parish from Sept. 3, 1979-July 22, 1980. Fr. Daniel Keelan became the pastor from 1980-1984 and was involved in restructuring the acolyte system. On June 19, 1984, Fr. George Gleason returned to the parish after service as temporary administrator for six months in 1971. Among the many accomplishments of Fr. Gleason was the construction of a rectory and social center complex, located south of the church. The dedication and blessing ceremonies were held on Apr. 6, 1986. Fr. Gleason celebrated his 40th jubilee on June 19, 1988. After the arrival of Fr. Dennis Mullen in 1988, St. Patrick's in Erin was clustered with St. Mary’s church and both parishes were served by Fr. Mullen. At this time Fr. Mullen and members began planning the renovation of the sanctuary at St. Mary’s church. On June 23, 1992, Fr. James Kraker was appointed pastor of St. Mary’s Church and St. Patrick's. Fr. Kraker completed the remodeling of the sanctuary. In 1994, the parish financial and pastoral councils agreed to expand the gathering area and make other needed improvements. The project was completed in June 1996.
Joseph Paron was ordained as deacon on Nov. 21, 1992. Deacon Joe assists at Mass as well as helping out in many other areas, such as the education department. Fr. Alois Gabrus, OFM, arrived in Sept. 1999. At that time, St. Patrick's of Erin was clustered with St. Mary’s Church in New Richmond. St. Bridget's of Wilson was clustered with St. Mary’s Church in Hammond. In 2002, St. Mary’s Church welcomed Fr. William J. Murphy. At this time, St. Bridget's in Wilson, St. John's in Glenwood City and St. Mary’s Church became a parish cluster. July 2010, Fr. Murphy retired form the priesthood. St. Mary's Church welcomed back Fr. Gerald P. Harris as pastor and started a new partnership being clustered with St. Bridget's of River Falls.