Prior to 1914, the spiritual needs of Butler area residents were served by two mission churches, St. Dominic's Marcy, and St. Martin's in Engelsburg. In May, 1914, Archbishop Sebastian G. Messmer, recognizing the growth in population that was spurred by the opening of the Butler railroad yards, announced that a new parish would be organized in "New Butler." Father Joseph Delaney was appointed pastor of the new parish which would serve 30-40 families. He arrived in July, 1914. Land for the new church was donated by George and Jennie Clarke, and St. Agnes was chosen as its patroness in memory of their eldest daughter.
A barracks church was erected in one day during the summer of 1914, and a parish picnic was held. Annual picnics quickly became a tradition. Construction of a permanent church began in late spring, 1915 and proceeded rapidly. The church was dedicated December 19, 1915.
St. Agnes School began in September, 1915. Classes were first held in a local hotel and, finally, in two rooms at the rear of the new brick church. The first teachers were Agnes Clarke and Jessie Hayes. The Sisters of Mercy arrived to teach at St. Agnes in 1921 and remained until 1926 when they were needed to teach at the recently opened Mercy High School.
Lay teachers again were hired until four Notre Dame Sisters arrived in 1928. With the exception of the years 1934-1942 when the school was forced to close due to the critical financial condition of the parish, Notre Dame Sisters have continued to teach at St. Agnes. When the school reopened in 1942, there was a need for new and expanded facilities. An attempt was made to haul an existing barracks to the church property, but it collapsed along the way. In 1943, a four-room school was erected on a site north of the church.
The housing surge and the migration to the suburbs that followed World War II resulted in unprecedented growth for St. Agnes. Between January, 1948 and August, 1951, 150 families registered as new parishioners, virtually doubling the size of the parish. As school enrollment increased from 235 in 1951 to nearly 1,000 in 1963, an ambitious building program was undertaken to accommodate the growing congregation. School facilities were expanded in 1952, 1957 and 1962. Construction in 1957 also included a new church, which we occupy today, and a convent. The 1943 school was demolished to provide space for the 1962 addition.
In October, 1962, Pope John XXIII convened the Second Vatican Council which significantly increased the involvement of lay members of the parish. The first Parish Council at St. Agnes was organized in January, 1970.
The original brick church was razed in 1979 in order to erect a parish activity center. Stained glass windows, crafted by a group of parishioners, were completed in 1988 and are installed in the church.
In 2000, St. Agnes celebrated 85 years as a faith community.