The prevalence of emotional and behavioural problems in secondary school adolescents is regarded as widely spread globally. Their effects/pitfalls are also a concern that cannot be ignored. Thus, this study dealt with this issue among adolescents, as well as with pitfalls and practices of secondary schools in Ethiopia, with particular focus on East Showa Administrative Zone of Oromiya National Regional state. Consequently, the study intended to:  examine what social competence problems (activity problems, social activities problems and academic performance problems) are experienced by secondary school adolescents of Ethiopia.  determine the relationship between sex groups and social competence problems by secondary school adolescents of Ethiopia.  examine the trends of emotional/internalising and behavioural/externalising problems among secondary school adolescents of Ethiopia.  determine the relationship displayed between sex groups and emotional/internalising and behavioural/externalising problems by secondary school adolescents of Ethiopia.  examine the relationship display between age groups and emotional/internalising and behavioural/externalising problems by secondary school adolescents of Ethiopia. To address the objectives of the study, a descriptive survey and correlational study were employed. To achieve this target, the Amharic and the Afan-Oromo versions of Achenbach’s (2001) youth self-report (YSR) were used to collect data from 714 research participants of secondary school adolescents out of 27,643 in the East Showa Administrative Zone of Oromiya Regional State-Ethiopia, from 8 secondary schools. In analysing the data, basic descriptive statistics such as frequency, percentages, percentiles and T-scores as well as ANOVA were employed. In general, the results of the study demonstrated that the prevalence of emotional and behavioural problems of Ethiopian secondary school adolescents was relatively lower (about 9%) in comparison to many other countries. Moreover, girls showed more internalising problems (11.58%) than boys (9.63%) and vice versa in externalising problems. Consequently, girls accounted for 8.6% who fell into a clinical category whereas amongst boys, 14.83% were classified into such as category. In contrary to the other findings males were scored higher than females in withdrawal/depressed subscales (4.23% and 2.74% respectively). Furthermore, statistically significant relationships between academic competences with activities, social activities, somatic complaints, social problems and externalising problems were discovered. Fulfilling and rendering appropriate guidance and counselling services in the schools comprised the first dimension of the recommendations of this work. Furthermore, establishing school based mental health services to alleviate the problems is another key point of the recommendation to assist adolescents with emotional and behavioural problems in secondary schools of Ethiopia. / Psychology / Ph.D. (Psychology)