This thesis consists of two volumes. The first is a literature review exploring the development of aggression in adolescent males with a summary of research that outlines a complex multi-factor trajectory across the lifespan towards aggression in males. The literature review focuses on how flawed social cognitive processes act as a proximal mechanism that facilitates aggressive and violent responses during social interactions and how a social information processing model has been proposed to explain aggression in adolescent males. The second paper presents findings for an empirical study of adolescent males with either high or low levels of aggression who completed a visual probe task with emotive facial image stimuli. The paper represents the first study employing a visual probe design with a sample of adolescent males identified with high levels of aggression. Findings revealed evidence of reduced attentional bias to angry expressions (angry) in those with high levels of aggression compared to non-aggressive controls. Implications for social information processing theory are discussed.