A large-scale study of complex "wh"-questions with 1,000 subjects aged 4-9 years is reported. The subjects' dialects were Mainstream American English or African American English, and approximately one-third were language impaired. The study examined when children permit long distance "wh"-movement, and when they respect a variety of syntactic barriers to movement. Thirteen different structures were compared, and the results suggest that typically developing children and disordered children at all the ages studied are capable of long-distance movement and obedience to abstract barriers. In no case was dialect a significant factor in the children's linguistic performance on these tasks.