Child maltreatment is linked to distinct neurophysiological patterns and social-emotional vulnerability. Relations among maltreatment, relative resting frontal alpha asymmetry, shyness, and psychopathology were examined prospectively. Adolescent girls (age 14-16) who experienced child maltreatment (N = 55) were compared to nonmaltreated controls (N = 25), and returned for 6- and 12-month follow-ups. Among participants exhibiting relative right frontal asymmetry, maltreated adolescents reported higher shyness than controls at Time 1. Low-stable and high-stable shyness trajectories were observed for maltreated participants. Compared to low shy, participants in high-shy trajectory reported at Time 3: higher neuroticism and generalized anxiety; and lower extraversion if they also exhibited relative right frontal asymmetry. Thus, right frontal brain activity and shyness are involved in social-emotional vulnerability of adolescents who experienced child maltreatment. [ABSTRACT FROM AUTHOR]