While research on mental health in sport has flourished in recent years (e.g., Vella et al., 2021), it often relies on cross-sectional designs, and there is limited work studying mental disorder among Canadian athletes. Research is also needed to understand the effect that Canadian sport environments can have on athletes' mental health. The purpose of this research was to explore the mental health experiences of elite Canadian athletes across three studies. Study one examined the prevalence of depression, anxiety, and eating disorders among elite Canadian athletes in December 2019 (ntime1 = 186), with the results indicating that symptoms of mental disorder were very prevalent among this population at baseline (~40%). Furthermore, stress and training load were correlated with symptoms of disorder. Study two examined changes in mental disorders over the following nine months across three additional timepoints (ntime2 = 142, ntime3 = 123, ntime4 = 108); data were analyzed using latent growth modeling. On average, symptoms of mental disorder did not change over time for athletes, although there were some sex differences in prevalence and change in disorder symptomology over time. Study three consisted of semi-structured interviews with 32 Canadian athletes, with the results focusing on the role that sport environments play in influencing athletes' perceptions of stigma, their willingness to seek help, and their overall mental health experiences. Together, these studies provide a more complete picture of athlete mental health and may inform interventions and policies designed to support athlete mental health.