John Patrick McGreevy, the second of the three children of Martin John and Margaret Mary (Brennan) McGreevy, was born in New York City (Bronx) on 5 April 1937. His early education was at Our Lady of Refuge School (Bronx) and Fordham Preparatory School (Bronx). He spent two years at Loras College, Dubuque, Iowa, before entering the Order of Preachers at Saint Peter Martyr Priory, Winona, Minnesota, on 30 August 1957, when he was given the religious name, Gerald. On 31 August 1958, he made his simple profession, and was assigned to Saint Thomas Aquinas Priory, River Forest, Illinois, for philosophical studies, earning a B.A. degree in philosophy at the Pontifical Faculty there. He made his solemn profession there on 31 August 1961, and was assigned to Saint Rose of Lima Priory, Dubuque, Iowa, for theological studies, where he was ordained to the priesthood on 18 April 1964, and continued his theological studies for a year.

Father McGreevy received his first assignment in 1965 - teaching in the English department of Fenwick High School, Oak Park, Illinois. He interrupted his teaching for a year (1967-1968) to attend Fordham University, New York City, where he earned a M.S. degree in educational administration. Returning to Fenwick High School, he soon entered the administration of the school, serving as Assistant Principal and Director of Studies (1969-1971), Principal (1971-1975), and President Principal (1975-1979). During this time he also served as president of the Illinois Association of Catholic Secondary School Principals and as a member of the Illinois State Committee of the North Central Association of Colleges and Schools. From 1980 until 1995 Father McGreevy was assigned to Providence College, Providence, Rhode Island, where he served successively as Assistant to the President, Vice-President for Student Services, Vice-President for Institutional Relations, Assistant Dean and Director of Special Credit Programs and Non-credit Programs in the School of Continuing Education, and Assistant Dean of Undergraduate Studies.

In 1995 he was assigned to Saint Vincent Ferrer Parish, River Forest, Illinois, where he served first as parochial vicar and then as pastor. In 1998 he was named pastor of Saint Gertrude Parish, St. Clair Shores, Michigan, a position which he held until 2009. He was then assigned to Saint Dominic Priory, Denver, Colorado, where, although on limited service, he did pastoral supply work and served as chaplain to Francis Heights Assisted

Living Center, as well as being the Conventual Lector for the priory. Because of his sharp mind and incredible memory, Father McGreevy was a living history and shared many details of the lives of the brethren and institutions of the province and especially for Fenwick High School.

Father McGreevy had fallen and broken his leg while in Michigan and in June 2014 he began to experience complications from this accident. In April 2016 the complications became increasingly severe and he experienced a gradual decline in health until his death on 21 July 2016. The Dominican and parish communities gathered for Office of the Dead that was sung preceding the Funeral Mass at Saint Dominic Parish on 25 July 2016 with Father Louis Morrone, O.P, Socius and Vicar Provincial, presiding, and Father Ed Ruane, O.P., Pastor, preaching. Funeral arrangements were handled by Horan & McConaty Funeral Home. He was buried in the Dominican Plot at Mount Olivet Cemetery, Wheat Ridge, Colorado.