On February 24, 1950, the Most Reverend William P. O'Connor, Bishop of Madison announced the formation of immaculate Heart of Mary Parish. It comprised 25 square miles, which formerly were part of St. Bernard's congregation. The Reverend Jerome Mersberger, then an Assistant at St. Bernard's, was named the Pastor. A census of the new parish had revealed the presence of more than two hundred Catholic families living within these boundaries.
The first general meeting was held on March 19, 1950. A chicken coop, on the Joe Fix farm on the south side of West Dean avenue was the first chapel and a vacant farmhouse on the property was to serve as the rectory. The first Sunday Mass was offered on June 16, 1950.
The Catholic Diocese of Madison purchased six acres of land in the village of Monona for the parish, formerly part of the Ellestad and Seeliger farms. The first building on the property included a temporary rectory, auditorium/gymnasium and a chapel. A Groundbreaking ceremony was held on September 12, 1950, Feast of the Most Holy name of Mary. The building was completed and dedicated on September 23, 1951. By 1954, 700 families were registered and the need for an elementary school was formalized. An attached school building was completed and opened for classes in the fall of 1954. It contained seven classrooms and a teacher's room. It was under the direction of the School Sisters of St. Francis. In 1956, a playground and parking lot were constructed. In May 1959, planning began for a Church and School addition. Ground was broken for the Church on December 10, 1959. In May 1961, the Church building was completed and dedicated. An addition adding six more classrooms to the school was completed in 1962. The parish had grown to 1200 families.
A rectory was constructed in July 1968 and the parish office and the liturgy office were moved from the school building. In 1968, Msgr. Edward Bier succeeded Fr. Mersberger as Pastor. In the mid 1970's a Director of Religious Education was appointed. Also, the attrition of the School sisters of St. Francis forced the administration to begin hiring lay teachers. In July 1985, Msgr. Bier died. The Rev. Robert Gille was appointed his successor.
A Director of Youth Ministry was appointed in 1990, and a Pre-School program was begun. In 1993, Rev. John Meinholz replaced Rev. Gille. In 2000, IHM parish celebrated its 50th Jubilee of service to the community. It has grown into a faith community of an accredited elementary school for K-8, with additional weekly religion programs for K-12 for those children attending public school. IHM also has a Music Ministry, an Adult and Youth Education Ministry, a social action program, outreach programs in S.H.A.R.E. Ministry, and a website.