ABSTRACT Background The International Olympic Committee developed the Sport Mental Health Assessment Tool-1, encompassing the Athlete Psychological Strain Questionnaire (APSQ) – used for initial screening of mental ill-being symptoms and risk in elite athletes. Despite preliminary psychometric evidence, the APSQ has yet to be tested in non-elite amateur athletes, who represent the majority of sporting participants. Method Athletes (n = 605) aged 28.57 years (SD = 9.32) comprising 402 males (73.5%) completed the 10-item APSQ, alongside validated measures of anxiety, depression and well-being. Two Confirmatory Factor Analysis models were tested, in addition to a series of receiver operating characteristics curves benchmarked against clinically relevant anxiety and depression symptoms to examine pre-defined and alternative cut-point sensitivity values. Nomological validity was tested through Pearson's correlations, and intraclass correlation coefficients were examined for test–retest reliability. Results A higher-order APSQ model comprising a general “Psychological Strain” factor, and three subcomponents of “External coping”, “Self-Regulation” and “Performance” were selected. Convergent and divergent validity were shown, and a new revised cut-point was found to have good classification accuracy within the sample. Largely “fair-to-good” test–retest reliability values were found. Conclusion The APSQ could be considered for initial screening of athlete mental health symptoms by sports organisations and may enable effective triaging to follow-up mental health assessment and/or supporting guidance, potentially preventing, or mitigating, short and long-term effects of mental ill-being. Further research should be undertaken to establish if the psychometric properties found amongst the present sample are generalisable to the broader amateur sporting population.