What is the best way to go from Chartres to CDG Airport (we don't have a car)? We need to catch a 2:15 PM plane to the U.S. Merci!
I would take the train.
Take a regional train from Chartres to Paris and the RER B from there to CDG, being sure to arrive a full three hours before your flight's scheduled departure time. There is a regional train that leaves Chartres at 08:52 and arrives at Gare Montparnasse at 09:53. Take either metro line 4 or 6 from Montparnasse-Bienvenue to Denfert-Rochereau and the RER B from there to either CDG 1 or CDG 2 TGV (which one depends upon from which terminal your flight will depart). Be aware that the RER B line divides northeast of Paris so be sure to get on a train that is going to CDG. It will take you just under an hour to get frrom Gare Montparnasse to CDG.
Ditto the train advice, And while there I highly recommend the Malcolm Miller tour of the Cathedral! Have a great trip, Ross in Denver
Oh, and the train station in Chartres is a short walk from the Cathedral and the heart of town.