Birth order and socio demographic characteristics play a substantial role in individual life because the family is the first social system to which an individual is exposed. The aim of this study was to assess the effect of birth order and socio demographic characteristics on anxiety and depression among adolescents. Design: descriptive correlational design was utilized. Setting: The study was conducted at two secondary schools at El-Batanoon, Shebin EL-Kom Menoufiya Governorate. Sample: convenience sample of all available adolescents from the two mentioned schools. Tools of data collection: (1) A semi – structured interview schedule to assess sociodemographic data, (2) Beck depression scale to assess depressive symptoms and (3) Taylor anxiety scale to assess anxiety. Results: The results revealed that twenty three percent of the study adolescents have severe anxiety while a slightly more than half (53.25%) have mild depression. There is positively significance correlation coefficient between anxiety and depression. There is significant relation between socio demographic characteristics of study adolescents and both anxiety and depression. There is no statistically significant relation between adolescents’ birth order and their level of anxiety and depression. Conclusion: It was concluded that there is no relation between birth order and both anxiety and depressive symptoms while there is significant relation between socio demographic characteristics and both anxiety and depression among adolescents. Recommendation: An educational program for adolescents at schools should be provided to increase their awareness about the needs and problems of adolescents and how to satisfy their needs and adapt with their problems.