When did France get involved in the American Revolution?

During the Revolutionary War, the French decided to send substantial help to the American freedom-fighters only in 1777, several years after the start of hostilities. Not wishing to support a doomed cause, and waiting to see how spirited the Americans would (and could) resist British force, the French were convinced by the American victory at Saratoga that lending support would be a worthy investment in American and their own efforts against the British.