The Pern stories, in reality, jump time spans quite a bit. They range from a collection of short stories that includes the tale of Pern's original survey team to novels that take place several years into the Ninth Pass- some twenty-four hundred Turns later. The difference in time gives each book a unique feel - Dragonsdawn and First Fall both feel Science Fiction, while the Dragonsinger trilogy feels more like fantasy, even though it is classified as Science Fiction. Anne McCaffrey does not necessarily write her Pern novels in chronological order - nor would I suggest that they be read that way. The best order, in my opinion, is the order I happened to stumble on when I first discovered Pern, more or less. Listed below are all the Pern novels, in the order that I suggest reading them. Enjoy Pern!
DragonsongOther Pern related books that are wonderful for the fanatic include The Atlas of Pern with Karen Wynn Fonstadt, All the People of Pern, and The Dragonlover's Guide to Pern (now available in two editions) with Jody Lynn Nye. The Girl Who Heard Dragons and Get Off the Unicorn are both short story collections that contain Pern stories.