Moral disengagement is a selective process that absolves feelings of guilt following transgressive conduct. Through absolving guilt, moral disengagement can also minimise experience of adverse outcomes. However, the moral disengagement process is not always successful. In some circumstances, transgressors may initially enlist moral disengagement but are unable to sustain the process, thereby increasing risk of experiencing the adverse outcomes that typically follow transgressive conduct. This thesis explores associations between moral disengagement and mental health in transgressive conduct, and the factors that may inform its enlistment over time, and across contexts. These issues are canvassed across seven chapters comprised of five studies prepared for publication.Chapter One introduces the existing literature on moral disengagement and provides a foundation for the subsequent studies comprising this thesis. Chapter Two presents findings from a meta-analytic review of 157 studies examining moral disengagement in youth (N = 118,501, aged 7-25 years). Results identify 35 distinct correlates involving behavioural outcomes, and personal and environmental factors that may moderate enlistment of moral disengagement. Extending on the meta-analytic findings, Chapter Three employs an experimental design of undergraduate students (N = 684, aged 17-25 years) to explore interactions between moral disengagement and negative self-evaluation on psychological distress. Chapter Four (N = 307, aged 17-25 years) further extends the literature, considering the function of moral disengagement in attenuating guilt in moral transgressions that profoundly violate personal moral standards, beyond everyday transgressions. To further examine the outcomes of moral disengagement following profound transgressions, Chapter Five first presents the development and evaluation of a measure (N = 500, aged 17-25 years) assessing symptoms of moral injury in youth, before examining links between moral disengagement and moral injury in Chapter Six. This final study (N = 75, aged 17-23 years) investigates interactions between emotion dysregulation and moral disengagement, and their impact on symptoms of moral injury across time. Findings highlight importance of accounting for different contexts in which moral disengagement is enlisted, issues around the sustainment of moral disengagement over time to attenuate adverse outcomes, and the role of emotion dysregulation in facilitating distress, particularly if moral disengagement fails.Together, these chapters position moral disengagement as a contextually embedded process that can only absolve transgressors of distress if sustained over time. Failure to sustain moral disengagement can result in transgressors experiencing significant adverse outcomes, particularly when transgressions profoundly violate personal moral standards. These issues are interpreted in depth in Chapter Seven, which concludes with a discussion of strengths and limitations of this thesis, and implications on future theoretical and empirical research.