from
http://southwest.com/travel_center/baggage.html
Carryon Baggage
In keeping with new security directives from the TSA, strict limitations are being imposed on carryon items.
* Airline passengers may now carry only one bag plus one smaller, personal-type item onboard the airplane.
* Personal-type items include purses, briefcases, cameras, food containers, or laptops (case included).
* Southwest Airlines limits carryon bag dimensions to 10x16x24 inches.
* All Customers and Employees and their items are subject to a thorough, physical search.
* The following items are not considered carryon bags or personal-type items and are not counted against the one-bag plus one personal-type item limit:
o A child restraint device for a child who has been ticketed, who has a seat reserved, or for which complimentary, available space exists.
o Assistive/mobility devices for individuals with a disability. There is no limit to the number of assistive/mobility devices a Customer can bring onboard the aircraft.
o Outer garments or other wearable articles of clothing.
o Food for consumption during flight contained in disposable packaging.
o Walking canes or umbrellas.