To upgrade to Business Class on American Airlines, you need a ticket that allows upgrades (basic economy typically doesn’t). After booking, check your reservation online or in the app to see if upgrade space is available. You can use AAdvantage miles, systemwide upgrade certificates (if you have them), or pay a cash upgrade if offered. Elite AAdvantage members may get complimentary upgrades on some routes. If no seats are open when you request, you can join a waitlist and see if it clears before departure. Being flexible with flights and having higher status improves your chances.