As of 2005[update], it is the sixth-largest Catholic diocese in the United States, currently serving approximately 1.5 million people in 134 parishes.

[4] Richard Coote, the first colonial governor, passed a law at the end of the 17th century that mandated a life sentence to any Catholic priest.

[6] Catholic priests started appearing in Long Island in the mid-19th century, founding missions and parishes.

[7] The first resident priest in Suffolk County arrived in Sag Harbor in 1852 to provide support to Irish Catholic families working on the railroads.

[8] The Diocese of Brooklyn was erected by Pope Pius IX in 1853 from territory formerly a part of the Archdiocese of New York.

[16] As news of the project cost became public, Murphy invited a Newsday reporter and photographer to tour the apartment.

They reported that it included a large suite with a new fireplace with an oak mantel, a temperature-controlled wine storage cabinet, and a marble floored bathroom.

They also complained about Murphy's management style, the cost of his new apartment, the sexual abuse scandal in Boston[17] and his ban against Long Island Voice of the Faithful.

[20] In October 2017, Barres announced the creation of the Independent Reconciliation and Compensation Program (IRCP) for survivors of acts of child sexual abuse committed by clergy in the diocese.

[27] In May 2000, Reverend Andrew Millar, a retired priest residing at the rectory of St. Peter and Paul Roman Church in Manorville, was arrested on sodomy charges.

A parent had caught Millar sodomizing his 15 year old developmentally disabled son in a public bathroom at Tobay Beach in Nassau County.

[29] Reverend Michael Hands of St. Raphael's Parish in East Meadow was arrested in May 2001 on charges of sexual abuse and sodomy.

However, a few months later another diocesan official allegedly asked Hands to keep his accusations secret as the diocese wanted to reinstate Ribaudo.

[32] In November 2006, Reverend Thomas G. Saloy, an administrator at the Queen of the Most Holy Rosary Church in Roosevelt was arrested on charges of possessing child pornography.

[37] That same month, Bishop Robert E. Guglielmone of the Diocese of Charleston was named in a sex abuse lawsuit in New York.

A man accused Guglielmone, then a pastor at St. Martin of Tours Catholic Church in Amityville, of sexually abusing him when he was eight in 1978.

[43] In May 2020, a Nassau County Supreme Court justice allowed pending lawsuits against the diocese to proceed.

The justice rejected legal claims from the diocest that the Child Victims Act violated due process.

[44][45] In October 2020, the Diocese of Rockville Centre filed for Chapter 11 bankruptcy while facing more than 200 sex abuse cases.

The Diocese gathered funds for the payment by having all its parishes declare bankruptcy so that its insurers can repurchase policies from them.

Catholic Charities is one of the largest providers of affordable senior housing on Long Island, operating over 1,300 units.