Previous studies of polygamy and child mental health have primarily focused on younger children. The present studies are among the first to focus on adolescents. The first study involved 210 randomly selected Bedouin Arab adolescents (mean age 15.9), who were administered instruments assessing their family environment and mental health. The second study involved 182 Bedouin Arab adolescents in which the student participants completed a single instrument about themselves and in which the teachers of the students completed the Teachers' Report Form of the Child Behaviour Checklist by Achenbach. The Bedouin Arab adolescents fell into two groups: (a) adolescents in monogamous family structures and (b) adolescents in polygamous family structures. The findings of the first study suggest that the two groups did not differ significantly in the majority of the assessed variables, even though there were significant differences obtained between groups for 4 of the 13 assessed variables. The two groups did not differ significantly in the second study. Results were discussed in terms of their cultural and developmental significance.