WHEN TO GO: Shenandoah National Park is open year-round, though visitor facilities are limited during the winter. Back-country camping is permitted at any time, with a permit. Big Meadows campground and Skyland Lodge have the longest seasons. The campground is open from March through December, the lodge from late March through November. Weekends in October, when the fall foliage is most colorful, are the busiest of the year, and traffic on the Skyline Drive can become bumper-to-bumper.

WHERE TO STAY: A park concessionaire, ARA-Virginia Sky-Line Co. of Luray, operates two very fine park lodges, Skyland Lodge and Big Meadows Lodge. Accommodations include cabins, cottages (for two to 10 persons), motel rooms and suites (for two to nine persons), with and without a view. A cottage room for two is $27.50 a night; a motel room for two is $52, plus $3.50 for each additional person.

The concessionaire also offers cottage rooms (with outside cooking area and picnic table) at Lewis Mountain. The rate for four persons is $32 a night; for six, $53.

For reservations:

Skyland Lodge, (703) 999-2211; Big Meadows Lodge, (703) 999-2221; Lewis Mountain, (703) 999-2255. Or, during winter months, (703) 743-5108.

CAMPING: There are four drive-in campgrounds in Shenandoah with a total of about 700 sites. They are Mathews Arm at Mile 22.2; Big Meadows at Mile 51; Lewis Mountain at Mile 57.5 and Loft Mountain at Mile 79.5. There are spaces for tents, trailers and recreational vehicles. Showers are available, except at Mathews Arm.

Reservations are taken only at Big Meadows (214 sites) and only from mid-May to mid-October. They can be made at park headquarters or at any Ticketron outlet, but no more than eight weeks in advance. The other three campgrounds are available on a first-come, first-served basis. The nightly fee is $7 for a campsite; Ticketron charges a $3.50 reservation fee.

Campers headed into the back country must obtain a permit (no charge), available from park entrance stations, visitor centers and park headquarters. Rangers may be able to direct you to parts of the park that are less heavily visited. They also will acquaint you with back-country regulations. For example: No open fires are permitted; you should carry a small camping stove. Drinking water from streams should be boiled rapidly three to five minutes. You must pack out any trash; it should not be burned or buried.

WHERE TO EAT: Both Skyland Lodge and Big Meadows Lodge have attractive dining rooms, serving good meals at a reasonable price. There is also a dining room at Panorama (Mile 31.5) and snackbars and campstores at Elkwallow Wayside (Mile 24.1); Big Meadows Wayside (Mile 51.3); Lewis Mountain (campstore only, Mile 57.6); and Loft Mountain Wayside (Mile 79.8).

ACTIVITIES: Throughout the summer, park rangers offer a variety of guided walks, campfire talks and other programs for visitors. Schedules are posted in visitor centers and published in the "Shenandoah Overlook," a free newspaper available at most park visitor facilities. You can fish in the streams and go horseback riding at the lodges.

INFORMATION: Visitor centers at Dickey Ridge (Mile 4.6) and Big Meadows (Mile 51) have exhibits outlining the park's history and its natural attractions.

A very informative, mile-by-mile guide, "Guide to Skyline Drive and Shenandoah National Park," by Henry Heatwole (Shenandoah Natural History Association, $4.50), is sold at the visitor centers and gift shops. It is the book new park rangers are given to acquaint them with Shenandoah.

To contact Shenandoah National Park headquarters: (703) 999-2229. For a short recording with information about park weather and campground reservations: (703) 999-2266.