The present study has two main objectives. First aim was to develop an indigenous scale to measure moral disengagement among adolescents and the second objective was to find out the predictive relationship among moral disengagement, dark triad and relational aggression among adolescents. Study-I was carried out to develop indigenous scale on moral disengagement among adolescents. The scale of moral disengagement was based on Bandura’s model of moral disengagement.Initially item pool of 90 items was generated by going through literature review based on previous scales developed on Bandura’s model and experts were also consulted to convert different dimensions of moral disengagement into culture relevant behaviors. Item pool of 90 items was turned into 76 items after expert evaluation and pilot testing. For finding highly correlated items in the first and second administration, sample of 284 adolescents between 12 to 19 years of age was selected. Finally, 40 highly correlated items were scrutinized. Factor analysis was carried out on sample of 400 adolescents, selected from different schools and colleges of district Gujrat. Exploratory Factor Analysis resulted into six factors comprising of 26 items (KMO= .8). Confirmatory factor analysis confirmed the same structure after deletion of two more items with good model fit indices (CFI= .902, CMIN/DF= 1.782, GFI=.923, AGFI= .901, RMSEA= .044) and six subcategories. Sub categories were labeled accordingly. Alpha reliability for full scale was .80 which indicate that scale is highly reliable.Study-II explored the predictive relationship among moral disengagement and dark triad with relational aggression. A sample of 612 adolescent students with age range 12-19 were selected from different educational institute of Gujrat, Pakistan. Newly developed moral disengagement scale for adolescents (MDSA) (Riaz & Bano, 2018), Dark triad personality scale short version (D3-short; Gul-E-Sehar & Fatimah, 2016) and the Urdu version of diverse adolescent relational aggression scale originally developed by Horton (2010) and translated by Riaz (2014) was used to measure relational aggression. The findings of the present study revealed significant predictive relation of moral disengagement [R2 =.327; F (1,607) = 295.362, p<.01], diffusion and displacement of responsibility sub dimension with relational aggression [R2 =.182; F (1, 608) = 135.060, p<.01],advantageous comparison with relational aggression [R2 =.135; F (1, 608) = 94.823-, p<.01],dehumanization with relational aggression [R2 =.199; F (1, 608) = 151.106, p<.01], ,attribution of blame with relational aggression [R2 =.134; F (1, 608) = 94.374, p<.01],moral justification with relational aggression [R2 =.110; F (1, 608) = 75.088, p<.01], and euphemistic labeling with relational aggression [R2 =.054; F (1, 609) = 34.742, p<.01] The current study also revealed significant predictive relation of Machiavellianism with relational aggression [R2 =. 220; F (1, 607) = 171.340, p<.01], narcissism with relational aggression [R2 =.189; F (1, 607) = 141.753, p<.01] and psychopathy with relational aggression [R2 =.265; F (1, 607) = 218.635, p<.01].Multiple regression analysis was carried out to find out the combined effect of moral disengagement and dark triad on relational aggression among adolescents. Findings revealed significant predictive relation of moral disengagement and machiavellianism with relational aggression [R2 =.423; F (2, 604) = 221.483, p<.01], with Moral disengagement and narcissism [R2 =.407; F (2, 604) = 206.882, p<.01], and with moral disengagement and psychopathy [R2 =.393; F (2, 604) = 195.887, p<.01].The present study supported the predictive relationship of moral disengagement and dark triad with relational aggression. These findings may have implication in the future intervention and prevention procedure for adolescents.