Youth hostel cards can be obtained from the American Youth Hostel Association either in person or by mail. The cost of the card is $20 for those 18 to 59, $30 for married couples and $10 for all others.

The annual fee entitles members to a free handbook that lists the 268 American youth hostels in 42 states. There are two volumes of the International Youth Hostel Handbook: Volume 1 covers Europe and the Mediterranean; the rest of the world is covered in Volume 2. Both handbooks include maps; each costs $6.95. There is also a combined edition available for $9.95. The handbooks provide information on making advance reservations.

Hostels require the traveler to own or rent a sleeping sheet. Rental rates vary, from a few cents a night to half a dollar. Sheets can be purchased at the Potomac chapter offices of the association for $10.

The International Youth Hostel Association also promotes group activities such as cycling, hiking, mountaineering and canoeing. We spent a week skiing in the French Alps at a hostel. The cost for seven nights lodging, with lift tickets, equipment rental, group instruction, nightly entertainment and three meals a day, was $200 each.

INFORMATION: American Youth Hostel Association, P.O. Box 37613, Washington, D.C. 20013-7613, (202) 783-6161. The Potomac chapter of AYH is located in Washington at 1017 K St. NW on the second floor. The phone number is 783-4943, and the hours are noon to 6 p.m. on Mondays and 10 a.m. to 3:45 p.m. Tuesday through Friday.