Hennessey was born on September 29, 1932, on a farm in
Buchanan County, Iowa. Her parents were Anna Killias Hennessey and Maurice Hennessey. She was the thirteenth of fifteen children born to her parents. Their parents modeled generosity to the poor, sheltering tramps who needed food during the depression. She also helped
Cesar Chavez, leader of the
United Farm Workers, organize migrant workers in
California. Hennessey taught in Chicago, Illinois, and studied at the
Jesuit School of Theology in Chicago (JSTC). While living in Chicago, she began to participate in the
nuclear disarmament movement as a member of the grassroots activist organization,
Clergy and Laity Concerned (CALC). Hennessey returned to Iowa in the 1980s where she helped establish the Catholic Peace Ministry, in Des Moines, and continued to be active in a variety of peace related activities. She then moved to New York City where she earned a master's degree from the Maryknoll School of Theology in New York, and worked as co-director of the Maura Clarke/Ita Ford Center. She later worked at the Appalachian Office of Justice and Peace, before returning to Dubuque, Iowa. == School of the Americas Protest ==