From the Introduction:
The Elemental Lands campaign setting is about choice. The players are encouraged to create unique and varied characters. This book presents many options for players, however, it should be noted that "the Lands" is a truly fantastical setting with a heavy interracial climate. Therefore, it is suggested that the players and GM be open to incorporating any race or prestige class found in other d20 books as well as reliable Internet sources. In fact, there are many great products from both big and small publishers that can be melded together to generate a truly unique role-playing experience for all involved.
In the Lands, many races were united as slaves under the rule of dragons and their sorcereous progeny. Since that time, the races have drifted apart, developing their own cultures. Still, many cities see all sorts of races within their gates. Therefore, PCs can play goblinoids, werecreatures, giants, etc., as long as the GM and player can come to an agreement about the inclusion of the character into the campaign. The same liberalization of prestige classes, feats, spells and other sources for gaming material should be integrated into an Elemental Land campaign. The only exception to this rule is the use of dragon creatures or halfdragon template characters. These creatures are extremely important to the history of the Lands, and as such, the author believes that the GM and players should agree that dragons and half-dragons be left as rare NPCs and creature encounters.