Sunday 20 FARMERS MARKET, sponsored by the Prince William County Park Authority. 8 a.m.-1 p.m., rain or shine. VDOT Commuter Lot at Center Plaza, Dale Boulevard, Dale City. 703-670-7115, Ext. 223.

Monday 21 AARP MEETING, Chapter 1384, 1:30 p.m., Woodbridge Senior Center, 13850 Church Hill Dr., Woodbridge. 703-791-7606.

TEEN ADVISORY COUNCIL, meeting to suggest future programs for middle and high school students, sponsored by the Prince William Library System. 7 p.m., Chinn Park Regional Library, 13065 Chinn Park Dr., Woodbridge. 703-792-4800.

LANDSCAPE PROGRAM, all about trees, sponsored by the Prince William Cooperative Extension Service. 7-8:30 p.m., Bull Run Regional Library, 8051 Ashton Ave., Manassas. Free; registration required. 703-792-6285.

STORY HOUR, for children 2-5, accompanied by an adult, sponsored by the Prince William Public Library System. 7:15 p.m., Chinn Park Regional Library, 13083 Chinn Park Dr., Woodbridge. Free. 703-792-4800.

Tuesday 22 PAGER ASSOCIATION, support group for parents of children with gastroesophageal reflux. 7 p.m., Conference Room 1, Wellness Center, Prince William Hospital, 8700 Sudley Rd., Manassas. 703-257-7691.

GENEALOGY RESOURCES WORKSHOP, an informal forum to share information about genealogy software, electronic resources and Internet sites, sponsored by the Prince William Public Library System. 7:30-8:30 p.m., Bull Run Regional Library, 8051 Ashton Ave., Manassas. Free; registration required. 703-792-4540.

LIBRARY STORY HOUR, for children 3-6, sponsored by the Prince William Public Library System. 10:30 a.m., Chinn Park Regional Library, 13083 Chinn Park Dr., Woodbridge. Free. 703-792-4800.

PARENTING CLASSES, for those with young children, sponsored by the Prince William Cooperative Extension Service. 7-9 p.m. Tuesdays through Nov. 26, Sudley North Government Building, 7987 Ashton Ave., Manassas. $35; registration required. 703-792-6288.

GMU INFORMATION SESSION, for students interested in transferring to George Mason University. 6 p.m., Room 202, Prince William Campus, George Mason University, 10900 University Blvd., Manassas. Free. 703-993-8375.

BULL RUN TROUBADOURS, 7:30 p.m., Trinity Episcopal Church, Battle and Church streets, Manassas. 703-753-2249.

LIBRARY BOOK DISCUSSION GROUP, "Georgiana, Duchess of Devonshire," by Amanda Foreman. Sponsored by the Prince William Public Library System. 7 p.m., Chinn Park Regional Library, 13065 Chinn Park Dr., Woodbridge. Free; registration requested. 703-792-4800.

HOME-BUYING SEMINAR, 7-8:30 p.m., Chinn Park Regional Library, 13065 Chinn Park Dr., Woodbridge. Free; registration required. 703-792-6287.

Wednesday 23 LIBRARY STORY HOUR, for children 3-7, sponsored by the Prince William Public Library System. 4 p.m., Chinn Park Regional Library, 13083 Chinn Park Dr., Woodbridge. Free. 703-792-4800.

LIBRARY PLAY, "Friends and Neighbors," presented by the Richmond Theatre Company, sponsored by the Prince William Public Library System. 11:15 a.m., Central Community Library, 8601 Mathis Ave., Manassas. Free; registration required. 703-361-8211.

FOR PARENTS LIVING APART, help on working out parenting decisions. Sponsored by the Prince William Cooperative Extension Service. 7-9 p.m. Oct. 23 and 30, Sudley North Government Building, 7987 Ashton Ave., Manassas. $35; registration required. 703-792-6288.

PARK AUTHORITY BOARD MEETING, 7 p.m., Prince William County Park Authority headquarters, 14420 Bristow Rd., Manassas. 703-792-4296.

PRINCE WILLIAM CHESS CLUB, 7-9 p.m., Potomac Library, 2201 Opitz Blvd., Woodbridge. 703-670-5887.

TOASTMASTERS INTERNATIONAL, Lake Ridge Club No. 8913. 7:30 p.m., Tall Oaks Community Center, 12399 Hedges Run Dr., Lake Ridge. 703-494-5530.

WRITERS GROUP, 7:30 p.m., Borders Books & Music, 2904 Prince William Pkwy., Woodbridge. 703-897-8100.

COMPUTER CLASS, how to buy and use a computer, sponsored by the Prince William Public Library System. 7 p.m., Central Library, 8601 Mathis Ave., Manassas. Free; registration required. 703-361-8211.

Thursday 24 FARMERS MARKET, 7 a.m.-1 p.m., Thursdays through Nov. 30, Church Street, next to the fire station in Old Town Manassas. 703-361-6599.

Friday 25 HEALTH-CARE JOB FAIR, sponsored by the Prince William Health System. 10 a.m.-3 p.m. in the former Marsteller Middle School gymnasium, 8730 Sudley Rd., Manassas. 703-369-8579.

HALLOWEEN SARAFI, take a family hike in the Bull Run Mountain Natural Area, with live music, face painting and more. Sponsored by the Friends of Bull Run. 7-9 p.m., today and Saturday, Bull Run Mountain House, 17405 Beverly Mill Dr., Broad Run. $5, children 1 and younger, $1. Reservations and flashlights required. 703-753-2631.

USED BOOK SALE, sponsored by the Friends of Chinn Park Library. 10 a.m.-4:30 p.m. today and Saturday, Chinn Park Regional Library, 13065 Chinn Park Dr., Woodbridge. 703-792-4890.

FREAKY FRIDAY, geared to children 12 and younger, with a community trick-or-treat event, face painting, costume contest and more. Sponsored by Old Town Manassas. 6:30-8:30 p.m., Loy E. Harris Pavilion, Center and West streets, Old Town Manassas. Free. 703-361-6599.

HAUNTED MINI-GOLF, with glow-in-the-dark balls, sponsored by the Prince William Park Authority. 7-10 p.m. today and Saturday, Lake Ridge Park Mini-Golf Course, 12350 Cotton Mill Dr., Lake Ridge. $5; spectators, $2. 703-494-5564.

HAUNTED TRAIL, for all ages, sponsored by the Prince William Park Authority. 7:30-10:30 p.m. today and Saturday, 6:30-9:30 p.m. Sunday. Prince William County Stadium Complex, One County Complex Ct., Woodbridge. $5. 703-792-7275.

LIBRARY MOVIES, for ages 3-7, sponsored by the Prince William Public Library System. 10:30 a.m., Chinn Park Regional Library, 13065 Chinn Park Dr., Woodbridge. Free. 703-792-4800.

USED BOOK SALE, sponsored by the Friends of Potomac Library. 10 a.m.-4 p.m. today and Saturday, noon-2 p.m. Sunday. Potomac Library, 2201 Opitz Blvd., Woodbridge. 703-494-8126.

BACK DOOR FRIENDS, noon, River Woods Community Center, 16573 Nanticoke Rd., Woodbridge. 703-221-5513.

Saturday 26 RECOVERY INC., for people experiencing anxiety, depression, fear and other emotional problems. 10 a.m.-noon, Cokesbury United Methodist Church, 14804 Blackburn Rd., Woodbridge. 703-490-5423.

OKTOBERFEST, a celebration of German culture, with food, music and entertainment. 11 a.m.-6 p.m., Loy E. Harris Pavilion, Center and West streets, Old Town Manassas. $5; children 11 and younger, free. 703-737-7600.

GENEALOGY RESOURCES WORKSHOP, highlighting genealogical research in European records, sponsored by the Prince William Public Library System. 2-4 p.m., Bull Run Regional Library, 8051 Ashton Ave., Manassas. Free; registration required. 703-792-4540.

FARMERS MARKET, 7 a.m.-2:30 p.m. Saturdays through Nov. 30. Church Street, next to the fire station in Old Town Manassas. 703-361-6599.

-- Compiled by Camille Ross

Items are accepted on a space-available basis from public and nonprofit organizations only, and must be received at least 14 days before the Sunday publication date. Submit information to: This Week, The Washington Post, 9420 Battle St., Manassas, Va. 20110. Include event name, dates and times, exact address, cost and a publishable contact phone number. For more information, call 703-392-1303.