The shooting occurred on Oct. 27, 2018, and killed eleven worshippers and wounded seven at the Tree of Life synagogue in Pittsburgh's Squirrel Hill neighborhood.
The gunman, Robert Gregory Bowers, opened fire with an AR-15 rifle and other weapons during worship services inside Tree of Life Synagogue, killing eight men and three women before a tactical police team tracked him down and shot him.
The Tree of Life building has remained closed since the massacre. The three congregations now worship at two nearby synagogues. Last week, Tree of Life leaders unveiled their vision for the damaged building: a rebuilt space for places of worship; memorial, education and social events; and classrooms and exhibitions.
The commemoration's theme is "Remember. Repair. Together." It includes a private Jewish service, studying the portion of the Torah that was to be read when the shooting happened, opportunities to do community service, and a public memorial service.
Several hundred people have registered to volunteer at various community organizations on Sunday. In Germany, the Clarion Quartet, comprised of Pittsburgh Symphony Orchestra musicians, will perform at a special event in Berlin.
Thousands are expected to participate in Sunday's remembrance through Pause with Pittsburgh, a virtual memorial event created by the Jewish Federations of North America.
Authorities charged Bowers, a truck driver from Baldwin, Pennsylvania, in the massacre.
Investigators say he posted criticism of Jewish immigrant aid society HIAS on social media before the attack, claiming the charity "likes to bring invaders that kill our people."
Federal prosecutors are seeking the death penalty.