Below you will find a list of favorite links to sites assessing advanced development in preschool aged children.
Gifted Development Center: Recognizing Giftedness in Young Children
Gifted Canada: How to Determine if your Child is Gifted
Parenting Gifted Preschoolers: Identifying Giftedness in Young Children
Brown's Stages: The Development of Morphology and Syntax (Verbal Milestones, very detailed)
Drawing Development In Young Children
Early Signs of Extreme Intelligence: by Kathi Kearney
General Information on Giftedness, not specific to Preschoolers, Toddlers or Early Development:
How Do I Know if My Child is Gifted?
Note The Difference: A Bright Child vs. A Gifted Learner (Comparison Table)
You Can Tell You're The Parent of a Gifted Kid When (a compilation of comments from parents)