Southwests frequent flier program is called Rapid Rewards. Customers receive one credit for each one-way trip (even though the flight may have stopovers). A free ticket, expiring after 11 months, is automatically issued when a member accumulates 16 credits in a 24-month period. Double Rapid Rewards credits used to be awarded for online booking, but this policy was modified at the end of 2003. At that time the bonus was reduced to .5 credit for each segment booked online, (i.e., each round-trip ticket booked online received a total of 3 Rapid Rewards credits). This was discontinued in April 2005. In addition, one-half credit is also earned for using a Southwest partner to book any car rental and/or hotel stay, regardless of whether a Southwest flight is involved. This arrangement has won numerous Freddie Awards over the years.

In February 2006, Southwest instituted capacity controls to redeeming its free tickets. This means that the airline limits the seats offered to frequent travelers using free certificates on each flight, whereas previously if there was a seat available, one could use the award, provided the passenger was not flying on one of the five blackout dates.