The study found that in this sample of Icelandic adolescents, 22 percent witnessed a severe verbal argument between their parents; 34 percent were involved in a severe verbal argument with their parents; 7 percent witnessed physical violence at home that involved an adult; and 6 percent of the sample was involved in physical violence at home that involved an adult. The findings also indicate that those adolescents who witnessed or were involved in an incident of verbal or physical violence experienced greater levels of depression, anger, and anxiety, and had lower levels of self-esteem. The aim of this study was two-fold: to develop a national base rate of intrafamilial verbal and physical violence at home among Icelandic adolescents; and to examine the effect of witnessing and/or experiencing such violence on the mental health and well-being of the adolescents. Data for the study were obtained from a sample (n=3,515) of 14- and 15-year-old adolescents in the national compulsory school system in Iceland. The students completed questionnaires detailing their experiences of severe verbal arguments and physical violence at home, and provided information on their backgrounds, behaviors, and mental health. The findings indicate that witnessing or being involved in severe incidents of verbal and physical violence affects the long-term emotional health and behavioral development of Icelandic adolescents. Implications for developing preventative measures to deal with the effects of intrafamilial violence in Iceland are discussed. Tables, figures, and references