This thesis examined the conscious processing hypothesis as a potential explanation for the way in which anxiety affects motor performance. The thesis is written as a series of research papers (studies). The five papers are preceded by a general introduction and followed by a general discussion. The first study replicated and extended previous research in the area of conscious processing. Participants acquired the skill of golf putting explicitly and implicitly across 400 trials. During a high anxiety transfer test, the performance of participants who learned explicitly was less robust than that of participants who learned implicitly, supporting the conscious processing hypothesis. Study 2 tested the conscious processing hypothesis using a performance rather than learning paradigm to control for possible desensitisation effects identified as a possible alternative explanation for the results of study 1. Results supported the conscious processing hypothesis, but an alternative attentional explanation was identified. Study 3 examined the conscious processing hypothesis while controlling for both desensitisation and attentional effects. Kinematic measures were also adopted to examine the golf putting task in vivo. Performance results partially supported the conscious processing hypothesis. Study 4 replicated and extended the design adopted in study 3. Study 4 also examined processing efficiency theory as a plausible alternative to the conscious processing hypothesis. Kinematic and cardiovascular measures were incorporated into the design. Performance scores suggested a processing efficiency interpretation. However, conscious processing effects could not be totally discounted. The fifth study examined the suggestion that the use of process goals by skilled but anxious performers might actively encourage lapses into conscious processing. Increases in state anxiety did not produce performance decrements. A lack of training in the use of goals was identified as an explanation for the absence of performance impairment. Implications for future research and applied practice are derived from the five studies.