Current evidence suggests that some school-age children are born with a sex chromosome variation. Large chromosome surveys of newborns indicate that 0.5% to 0.6% have chromosome errors, with sex chromosome variations accounting for 35% of them. The four most frequently occurring sex chromosome variations are Turner Syndrome (45, X), Klinefelter Syndrome (47, XXY), Polysomy X or Triple X (47, XXX), and Polysomy Y or XYY (47, XYY). Though many individuals with sex chromosome variations can live functionally normal lives, others may experience developmental, physical, psychological, behavioral, and learning impairments. New information has dispelled myths and biases previously associated with these disorders. By becoming knowledgeable about sex chromosome variations and their effects upon children, school health personnel can assist affected children, their families, and teachers.