The best price found from United States to St Lucia is on October 3rd, 2016, travelling with jetBlue. See more options, compare prices and book: search flights.
Confusingly, St Lucia has two airports:
Hewanorra International Airport in Vieux Fort is at the remote southern tip of the island. It handles flights from North America, the UK and Europe plus a few regional flights.
George FL Charles Airport is conveniently located in Castries but due to the short runway is only served by regional flights on prop planes.