The aim of this paper is to outline the development of Eysenck and Calvo's (1992) processing efficiency theory (PET) and to summarise research testing its predictions in the sporting domain. PET provides a mechanistic explanation for how anxiety may influence performance through its impact on attentional resources. The central tenet of PET is that as well as pre-empting resources in working memory, increased anxiety provides a motivational function, leading to the allocation of additional effort to attempt to maintain task performance. Research in sport settings has been supportive of the predictions of PET, adopting a range of measures of processing efficiency; including self-reported effort, secondary task performance and psychophysiological indices. Furthermore, cognitive sport psychologists have recently examined direct influences of anxiety on the efficiency of information processing via gaze behaviour analyses. These findings are particularly relevant in the light of a recent update and development of PET; attentional control theory (ACT; Eysenck, Derakshan, Santos, & Calvo, 2007). ACT purports that anxiety reduces attentional control by increasing the influence of the stimulus-driven attentional system at the cost of goal directed control. It is evident that ACT may provide a useful framework for examining the relationship between anxiety, attention and performance in sport skills.