The use of psychological interventions in competitive sport to enhance performance has become increasingly popular. However, the effectiveness of these interventions has been questioned by some sports psychologists. In general, educationally-based psychological interventions have produced significant increases in performance. Specifically, it was found that 38 of the 45 studies examined (85%) had found positive performance effects, although causality could only be inferred in 20 of these studies. These interventions could be classified as relaxation-based, cognitive, cognitive-behavioural or behavioural in nature. Although general support was provided for the effectiveness of psychological interventions in competitive sports, a number of methodological shortcomings limit the application of the findings. For example, future intervention research in competitive sport should employ more detailed manipulation checks, include follow-up assessments beyond a mere post-test, include placebo-control groups to control for expectancy effects and include more diverse samples. In addition to the empirical intervention research, recent research employing qualitative methodologies has greatly added to our understanding of the types of interventions and what type of sport psychology consultants most positively affect performance enhancement, as well as the personal growth of athletes. Continued quantitative and qualitative research needs to be conducted so that a better understanding is gained of how to conduct psychological interventions with athletes that will enhance performance as well as personal growth.