Millions of children are exposed to traumatic experiences each year. Over 30% of these children develop a clinical syndrome with emotional, behavioral, cognitive, social, and physical symptoms called posttraumatic stress disorder. The symptoms of posttraumatic stress disorder fall into three clusters: reenactment of the traumatic event: avoidance of cues associated with the event or general withdrawal; and physiological hyperreactivity. Significant physical and medical problems in childhood, adolescence, and adulthood appear to be related to childhood trauma. Current treatment approaches include postacute psychoeducation, individual psychotherapy, pharmacotherapy, and cognitive-behavioral therapy. Despite increasing attention over the past 10 years, childhood posttraumatic stress disorder remains an understudied public health problem.