A comprehensive assessment is undertaken concerning Norwegian studies on the mental health of immigrant children, youths, and young adults spanning the ages of 10 to 26 years. The principal aim is to assess inter-group as well as intra-group variations in symptoms of mental health problems (not clinically diagnosed psychiatric disorders) among preadolescents, adolescents and young adults who are either foreign born (first-generation immigrants) or born in Norway to two foreign-born parents (second generation). Included in the overview are studies based on the general immigrant populations as well as refugee groups, and unaccompanied minors arriving as asylum-seekers. It is determined that immigrant boys are especially vulnerable with respect to internalizing problems in elementary and junior high school years, while senior high school seems to be a sensitive period for immigrant girls. National group differences in reported internalizing problems were noted, particularly among the younger youths. In the older samples there was in general no support for the concept of a ‘migration morbidity association’. Thus, it appears that the question as to whether immigrant children and youth have more mental health problems than non-immigrants is highly dependent on national background and age group. It is recommends that future research should take a holistic, developmental approach in the study of psychosocial adjustment and mental health of immigrant background children and youth. In the Norwegian context, concepts such as ‘the immigrant paradox’ and ‘the migration morbidity association’ are generally of limited application toward shedding light on the topic of mental health of migrant children and youth.