Q: What is the cost of joining, and how do I enroll?

A: There is no cost to join a frequent flyer program.

You can enroll over the phone, via the Internet, or by mail. In the first two cases, you will receive a membership number immediately, your account will be activated, and you can earn miles for a flight later that same day. When enrolling via mail, it can take up to two months to receive your membership card and handbook.

Below, we've listed the Web addresses and phone numbers you'll need to enroll in the frequent flyer programs of the 12 airlines we cover.

Air Canada: 800-361-5373

Alaska Airlines: 800-654-5669

America West: 800-247-5691

American: 800-882-8880

Continental: 713-952-1630

Delta: 800-323-2323

Frontier: 866-263-2759

Midwest: 800-314-7125, 414-570-7000

Northwest: 800-447-3757

Southwest: 800-445-5764

United: 800-421-4655

US Airways: 336-661-8390