Objective: The Wechsler Preschool and Primary Scale of Intelligence -- Fourth Edition Australian and New Zealand Standardised Edition (WPPSI-IV[superscript A&NZ]) is one of the most widely used intelligence assessments for children aged 2 years 6 months to 7 years 7 months. Given the impact of clinical and placement decisions that are supported by WPPSI-IV[superscript A&NZ] results, it is important to provide evidence of criterion-related validity. Criterion-related validity refers to the degree to which test scores are associated with an external criterion (e.g., pre-existing diagnosis or classification). Method: Two studies of children with intellectual giftedness (n = 19) and intellectual disability (n = 15) were conducted to determine if the constructs measured by the WPPSI-IVA&NZ perform as expected in criterion groups with known characteristics. Results: Independent sample t-tests revealed mean composite scores for intellectually gifted children were significantly higher than matched controls, with the exception of the Processing Speed Index and Cognitive Proficiency Index. Children with intellectual disability on average obtained significantly lower mean scores on all composites relative to matched controls. Conclusion: Results indicated that the WPPSI-IV[superscript A&NZ] can provide valid estimates of intellectual ability for children with intellectual giftedness and intellectual disability that align with their previous diagnosis or classification.