Objective: Measuring the academic achievement gap between Americans and Canadians using the Wechsler Individual Achievement Test-Third Edition (WIAT-III) Objective: Examine the size and directionality of score differences on the WIAT-III, a comprehensive and widely used test of academic achievement, using American and Canadian norms. Method: 580 college and university students referred to a provincial assessment centre due to a possibility of Learning Disability (LD) or Attention Deficit Hyperactivity Disorder (ADHD) had their WIAT-III raw scores converted to standardized scores using American and Canadian norms provided by the test publisher's scoring program. Mean age of the students was 23.4 (SD = 8.7), 62.4% were female. Results: Differences between mean Canadian and American composite and subtest scores were minimal and directionality was consistent apart from mathematics. Small effect sizes were found for both composite scores and subtest scores. Scores obtained through the two sets of norms were not meaningfully different as 93–99% of the sample remained within +/− 5 points or within the same classification category when considering composite scores. Similar findings, with few exceptions occurred with subtest scores. Conclusion: No meaningful differences occurred between the composite or subtest test scores of a clinically derived sample of individuals scored using both the American and Canadian norms. This is at odds with what Harrison et al (2014, 2015) found for WAIS-IV scores and the test publisher's website statement regarding WAIS-IV Canadian-American discrepancies. Clinically, this suggests that Canadian practitioners can employ WIAT-III American norms for diagnostic purposes as the discrepancy between achievement scores is rarely large enough to alter classification categories.