The central questions addressed in this paper are whether present generations of adolescents and adults worldwide are at greater risk of developing suicidal reactions than previous generations were and what the possible causal mechanisms involved are. On the basis of data from international and national data banks as well as an extensive review of the literature, it is concluded that a true increase in suicide mortality and morbidity has occurred over the larger part of this century among the White urban adolescent and young adult populations of North America and Europe, particularly among (young) males over the last three decades. Among the possible causal mechanisms identified are (1) the corresponding increase in the prevalence of depressive disorders; (2) the corresponding increase in the prevalence of substance (ab)use and substance abuse disorders, and a lowering of age of onset of (ab)use; (3) psychobiological changes, in particular the dramatic lowering of the age of puberty; (4) an increase in the number of social stressors with extensive consequences for youth; (5) changes in attitudes towards suicidal behaviors and the related increased availability of suicidal models.