Turner syndrome (TS) is a condition that affects 1 in 2,500 females due to a loss of some X chromosome material. It is characterized by a number of common physical features, including short stature, sexual infantilism, and infertility, as well as by specific learning and behavior problems. This article compares abilities, achievement, behavior, and self-esteem in 67 children with TS and 27 nonaffected controls. Results indicate selective impairments in visuospatial and memory areas and significant underachievement in arithmetic, particularly numerical ability, mental calculation, geometry, and reasoning. Learning problems, a major concern for parents, were not being satisfactorily addressed at school. Poor social competence and increased behavior problems, particularly in the area of hyperactivity, were also noted. Although self-esteem was only marginally lower, issues related to poor peer relations were most problematic.