MUSIC Braintree: Island Grove Chorus performs a cappella and special guests the Dixie Diehards perform Dixieland in “Shine on Harvest Tunes.’’ Saturday, 7:30 p.m., at Braintree Viking Club, 410 Quincy Ave. $20, $15 in advance. www.islandgrovechorus.org.
Stoughton: The duo of Atwater-Donnelly will blend harmonies and play guitar, Appalachian mountain dulcimer, mandolin, tin whistle, harmonica, banjo, bones, spoons, and limberjacks in a performance sponsored by the Friends of the Stoughton Public Library and the Stoughton Cultural Council. Saturday, 2 p.m., at Stoughton Public Library, 84 Park St. Free. 781-344-2711, www.stoughtonpubliclibrary.org.
HALLOWEEN Quincy: At the Seventh Annual Harry Potter Halloween Party, walk the halls of Hogwarts, participate in a sorting ceremony, attend magic classes, enjoy a Halloween treats feast, and enter a prize drawing. Reservations recommended; event sells out. Saturday, 1 p.m., at Quincy Community United Methodist Church, 40 Beale St. $25 family of four or $8 per person, under age 4 admitted free. 617-773-3319.
Quincy: The Fourth Annual Monsters Ball and Halloween Costume Contest features music spun by DJs Texas Mike and G-spot, a mummy wrap contest and magic by the Magnificent Edoardo. Prize for best costume. Saturday, 8 p.m.-1 a.m., at Future Bar Music Lounge, 58 Ross Way. $10 in advance. 617-256-4093, www.futurebarmusiclounge.com.
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