ABSTRACT Context Certified athletic therapists in Ireland and Canada serve essential concussion assessment and management roles, but their healthcare practices and concussion knowledge are unestablished. Objective To examine Irish and Canadian athletic therapist cohorts: 1) concussion knowledge, 2) current concussion assessment and management techniques across all job settings, and 3) concussion assessment and management practices associations with years of clinical experience and highest degree attained. Design Cross-sectional cohort. Setting Online survey. Patients or Other Participants Licensed Irish (49.7%;n=91/183) and Canadian (10.1%;n=211/2,090) athletic therapists. Main Outcome Measures Athletic therapists completed an online survey assessing their demographics, concussion knowledge (symptom recognition, patient-clinician scenarios), annual concussions assessed, and assessment and return-to-play (RTP) measures using a modified, previously validated survey. Symptom recognition consisted of 20 (8 true, 12 false) signs and symptoms recognition questions scored as total correct. Descriptive statistics and odds ratios (OR) were used to examine survey responses where appropriate. Results Irish (86.8%;n=46/53) and Canadian (93.4%;n=155/166) athletic therapists indicated RTP guidelines as the most common method for determining RTP. Symptom recognition was 72.8±17.0% among Irish and 76.6±17.0% among Canadian athletic therapists. Irish (91.2%;n=52/57) and Canadian (95.3%;n=161/178) athletic therapists reported standardized sideline assessments as the most common concussion assessment method. Irish and Canadian athletic therapists' two-domain (Irish:38.6%[n=22/57]; Canadian:73.6%[n=131/178]) and three-domain (Irish:3.5%[n=2/57]; Canadian:19.7%[n=35/178]) minimum assessments (i.e. symptoms, balance, and/or neurocognitive) were not associated with education or clinical experience (p≥0.068), except for Canadian athletic therapists with Master's degrees having greater odds of completing two-domain assessments at initial evaluation than those with Bachelor's degrees (OR[95%CI]=1.8[1.41–1.95]). Conclusions Irish and Canadian athletic therapists demonstrated similar concussion knowledge to prior research; however, the majority did not fully adhere to international consensus concussion assessment guidelines as evidenced by low two- and three- domain assessment use. Athletic therapists should aim to implement multidimensional concussion assessments to ensure optimal healthcare practices and patient safety.