This chapter explores the mental health of athletes by examining the prevalence of mental health difficulties in athletes, the mental health difficulties that can affect athletes, why athletes might be vulnerable to these, how they can be prevented or treated, and how positive mental health and wellbeing can be promoted in sporting environments. It focuses on the mental health of athletes, rather than on the role of exercise in treating mental health in non-athletic populations. The recognition that athletes can experience mental health difficulties challenges the commonly held perception that athletes, particularly those competing at elite level, are unbreakable superior beings both physically and mentally. The term depression can cover a range of disorders that are generally characterised by a reduction in functioning and symptoms such as low mood, sadness, decreased energy, and feelings of worthlessness. Anxiety disorders are different from performance anxiety which is a common occurrence in competitive sport.