Anne McCaffrey's Pern series:

Reading order recommended by author:
Dragonflight
Dragonquest
Dragonsong
Dragonsinger
Dragondrums
The White Dragon
Moreta: Dragonlady of Pern
Nerilka's Story
Dragonsdawn
Chronicles of Pern: First Fall
The Dragonlover's Guide to Pern: "The Impression"
A Gift of Dragons: "Smallest Dragonboy"
A Gift of Dragons: "Girl Who Heard Dragons"
The Renegades of Pern
All the Weyrs of Pern
The Dolphins of Pern
Dragonseye
The Masterharper of Pern
A Gift of Dragons: "Runner of Pern"
The Skies of Pern
A Gift of Dragons: "Ever the Twain"
Legends II: "Beyond Between"

The following are co-written by Anne's son and literary executor, Todd McCaffrey:
Dragon's Kin
Dragonsblood
Dragon's Fire
Dragon Harper

Guides:
The Dragonlover's Guide to Pern
The Atlas of Pern
The People of Pern (Pern Portrait Gallery)