Adaptive behavior over time in 70 children with fragile X syndrome, ages 1 to 12 years, was examined using the Vineland Adaptive Behavior Scales. With a mean of 4.4 assessments per child, adaptive behavior skills increased steadily and gradually over time. Children with less autistic behavior and higher percentages of FMPR expression showed better performance on all areas of adaptive behavior. Children without autistic behavior displayed higher scores and rates of growth on the Daily Living Skills domain, with the lowest scores in Socialization. Comparison to Brief IQs indicate that children with fragile X syndrome display nonverbal IQs superior to their adaptive behavior when they are below age 10 but that these skills seem to converge as they get older.