All Arlington County public libraries will open three hours later than usual tomorrow. The delayed opening will enable library employes to attend a special staff meeting.

Arlington Central Library, 1015 North Quincy St., will open at noon and all branch libraries will open at 1 p.m. For more information, call 284-8181.

The Lady Fairfax Chapter of the American Business Women's Association will hold its annual fashion show and luncheon at noon Saturday at the Holiday Inn, Tysons Corner.

The show and luncheon will be a scholarship fund-raiser and will cost $13.75 per person. Door prizes will be awarded. Reservations will be accepted at 273-3026 or 241-3225.

The Mount Vernon Children's Theatre will stage its spring production of "Cinderella," with a cast of 39 children, ranging from age 7 to 17 and representing 16 schools.

The play will be performed at the Heritage United Presbyterian Church, 8503 Fort Hunt Rd., Alexandria, at 7:30 p.m. April 18 and 25; 1 and 4 p.m. April 19 and 26, and 2:30 p.m. April 20 and 27. Tickets are $4 per adult and $2.50 per child. Reservations may be made at 768-7689 at least three days before the performance. Tickets also may be purchased at the door.

The Overlee Preschool in Arlington will hold its 40th anniversary reunion from 2 to 5 p.m. April 19 on the school grounds at 2425 N. Glebe Rd. The reunion is open to all parents and former Overlee children. Arlington County School Board member Judy Connally, Fairfax County School Board Chairwoman Mary Collier and several other education leaders are expected to attend.

Overlee is one of the oldest cooperative preschools in the Washington area that provides a parental link between home and school. The preschool educates 2-, 3- and 4-year-old children and is one of 32 cooperative preschools that make up the Northern Virginia Council of Parent Participation Nursery Schools. For more information about Overlee Preschool, call Cathy Denk at 734-1825 or Joan Anthony at 241-8898.

There will be a KIDS Safety Day at Skyline Shopping Mall from 11 a.m. to 3 p.m. April 12 on Rte. 7 in Falls Church KIDS (Kids Identification Sign-Up) is a public service program sponsored by the International Council of Shopping Centers to teach preventive child safety tips.

The Fairfax County Police Department, the traffic division of the Division of Motor Vehicles, Arlington Hospital and Northern Virginia Doctor's Hospital will be on hand to offer tips.

Identi-kits, which provide permanent fingerprint records, will be available at no cost. MacGruff, the mascot of the Crime Prevention Association, will be on hand. Puppet shows will be performed and the 200-pound Officer Robot will give video safety presentations. Program topics include poison control, bicycle and car safety and first aid. For more information, call Carol Buchanan at 920-8500, ext. 6288.