As a first point of entry into an organisation, personnel selection is an important tool to identify positive and negative characteristics of job candidates. Three such negative characteristics are Machiavellianism, narcissism, and psychopathy, also known as the Dark Triad. These three traits reflect a core of callous self-interest, and have been associated with manipulation, deceit, self-promoting strategies, and interpersonal conflict. The Dark Triad represents a risk for organisations in terms of how those possessing high levels of DT may manifest damaging behaviours when entering or existing within the workplace context. As of yet, few studies have examined how the Dark Triad manifests within a personnel selection context. Consequently, this thesis examined how aspects such as selection outcomes, peer ratings of leadership competencies, and performance ratings were related to selfreported Dark Triad scores over the course of a five day assessment centre in a large public sector organisation. The main research question investigated in this thesis was how the Dark Triad is related to personnel selection outcomes, in particular how Dark Triad traits are related to others’ perceptions of behaviour. Results revealed that narcissism was perceived positively by others, and was related positively to success on selection. In contrast, psychopathy had negative relationships with a number of outcome variables including success on selection, peer-ratings of effort and comradeship, and ratings of awareness of others. Peer-ratings of the Dark Triad were found to be lower than self-rated Dark Triad scores. Final recommendations by expert assessors were positively related to narcissism but negatively related to psychopathy, in line with expectations. These results respond to research questions associated with how the Dark Triad is related to selection outcomes and perceptions of others, identifying three main themes which have emerged from this thesis. Firstly, success of job candidates is more positively associated with the narcissism trait, while psychopathy was detrimental to the success on the selection process. The second theme was associated with the differences between peer ratings of the Dark Triad and self-ratings of the Dark Triad with individuals rating themselves higher on the Dark Triad. Lastly, in general, narcissism was perceived as more preferable by others while psychopathy more unfavourably. The implications noted in the final chapter relate to organisations considering screening options to identify those scoring high on Dark Triad measures, and the impact on selection decisions particularly for public sector organisations which tend to rely on a hierarchical structure. In addition, how others might report on perceived Dark Triad behaviour, and the ways in which ratings of leadership competencies are related to Dark Triad traits are aspects organisations may also wish to consider. These implications are limited by lower than expected effect sizes, and thusly further studies examining these outcomes may provide a clarity on the relationships identified in this thesis. Practitioners may consider taking note of the main Dark Triad traits associated with selection outcomes, as well as how Dark Triad traits may be initially perceived positively by peers and subject matter experts alike.