This imposing brick structure was completed at the southeast corner of 30th Street and Linden (49th) Avenue In 1908, the Sisters moved from their living quarters in the school building into a new convent which had been constructed at 3009 South 49th Court. The Polish population of the South Lawndale area of Chicago, on Cicero's east boundary, increased to such an extent that in 1907, the Archdiocese of Chicago organized Good Shepherd parish at 28th Street and Kolin Avenue from portions of St. Mary of Częstochowa and St. Casimir parishes. In 1911, Polish families who formerly belonged to St. Mary of Częstochowa organized the national parish of St. Valentine at 13th Street and 50th Avenue. On July 24, 1915, 800 employees of the Western Electric Company died as the Eastland excursion boat capsized in the Chicago River. Twenty-nine parishioners lost their lives in that tragedy and were remembered in a memorial Mass. In June 1916, the parish broke ground at the southwest corner of 48th Court and 30th Street for a magnificent Gothic revival structure. When the cornerstone of this edifice was laid on October 29, 1917, work was nearing completion on the present rectory at 3010 South 48th Court. Archbishop George W. Mundelein dedicated St. Mary of Częstochowa Church on March 10, 1918. Hundreds of Poles gathered in the silver-bedecked church of St. Mary on May 31, 1920, to celebrate the 25th anniversary of the founding of their parish. Membership then numbered 800 families with 900 children enrolled in the school. A history of St. Mary of Częstochowa parish written in 1920 contained the information that "At present this parish consists of the church with its contents worth $135,000.00; school, worth $85,000.00; rectory, which is worth $30,000.00; convent, worth $25,000.00; frame ex-church [the parish hall]... worth $3,000.00; and lots worth about $25,000.00. Total worth,$303,000.00"  Father Czajkowski continued to serve as pastor throughout the Great Depression, a hard time for his parishioners who keenly felt the effects of factory closings in Cicero. He died October 13, 1939, at the age of 65. Francis Nogajewski served as administrator of the parish until July 1940, when Rev. Theodore F. Langfort was named pastor.