Emotional intelligence (EI) has been reliably associated with better mental health (Martins, Ramalho, & Morin, 2010) however the nature of this relationship in adolescence remains largely unexplored. The small body of existing adolescent research is disproportionately focussed upon the 'trait' versus 'ability' EI perspective and the association with mood (versus behavioural) disorders in the form of simple, descriptive relationships that reveal little about the processes underpinning such adaptive outcomes. This research redresses this imbalance and advances the field by examining how (whether directly or indirectly linked to known stress-illness processes) and when (under which stress conditions) EI (in both 'forms') might be associated with better adolescent mental health, whilst simultaneously exploring the conceptualisation of EI within this developmental period. Adult literature is equivocal on both fronts. Firstly, evidence points to differential incremental contributions from ability and trait EI in the prediction of internalising versus externalising symptomatology beyond known correlates of performance, i.e., personality and cognitive ability (e.g., Gardner & Qualter, 2010; Peters, Kranzler, & Rossen, 2009). Secondly, whilst there is some evidence to suggest that trait EI may directly attenuate the effects of chronic and acute stressors to promote adaptation (e.g., Mikolajczak, Roy, Luminet, Fillée, & de Timary, 2007), the role of ability EI in this regard appears unclear (e.g., Matthews et al., 2006). Indirect links to adjustment are also hinted at; coping mediates trait EI-health outcomes in youth though not all EI-influenced 'adaptive' coping styles (e.g., problem-focussed) appear to contribute to this effect (e.g., Downey, Johnston, Hansen, Birney, & Stough, 2010). Using cross-sectional, self-reported data from 1,170 adolescents (mean age = 13.03 years; SD = 1.26) the present research aimed to address this lack of clarity. Preliminary regression analyses found that collectively, EI made a significant, incremental contribution to the prediction of depression and disruptive behaviour in youth beyond the influence of higher-order personality dimensions and general cognitive ability. However, of the two, trait EI appeared the stronger predictor. Structural equation modelling of conditional indirect effects found that whilst both forms of EI can buffer the effects of stressors (family dysfunction, negative life events, socio-economic adversity) on disorder, the mechanisms by which this beneficial effect operates differs substantially according to context - effects appear contingent on stressor, health outcome and level of EI. For depression, ability EI influences the selection of avoidant coping when facing family dysfunction and negative life events, whilst trait EI modifies the effectiveness of active coping under family dysfunction only. In contrast, EI directly attenuates the effects of stressors on disruptive behaviour. Nevertheless, the results of supplementary path analyses augur for the importance of both forms of EI in adaptational processes; actual emotional skill (as ability EI) appears dependent on perceived competency (trait EI) to realise advantageous outcomes. Implications for the EI construct and related intervention programmes are discussed together with recommendations for progression of the field.