Cell phones are convenient and increasingly more intuitive to operate. They come in hip, fanciful little packages with a growing range of extra features that deliver music, video, messaging, and Internet capabilities. Children have them, and some grownups are hooked by them. Adolescents and young adults are obsessed with and possibly addicted to the cell phone. The question of whether the brains of children are more susceptible to the radio-frequency fields emitted by cell phones than are those of adults remains open, and cannot be easily answered based on existing scientific knowledge. Obsessive, problematic, or excessive cell-phone use and functional impairment in adolescents have been observed worldwide.