Objectives: Performance on neurocognitive tasks develops with age, but it is still unknown whether this performance differs between children from different cultures. We compared cross-sectionally the development of neurocognitive functions in 3- to 15-year-old children from three countries: Finland, Italy, and the United States (N=2745). Methods: Language, face memory, emotion recognition, theory of mind, and visuospatial processing subtests from the NEPSY-II standardizations in Finland, Italy, and the United States were used to evaluate if children and adolescents from different linguistic and cultural backgrounds differ in performance on these measures. Results: We found significant differences in performance on the tasks between the countries. Generally, the differences were more pronounced in the younger age groups. Some subtests showed greater country effects than others, performance on these subtests being higher, in general, in one country over the others, or showed different patterns of age associated changes in test performance. Conclusions: Significant differences in neurocognitive performance between children from Finland, Italy, and the United States were found. These findings may be due to cultural or educational differences that impact test performance, or due to factors associated with the adaptation of measures from one culture to another. The finding of performance differences across countries on similar tasks indicate that cross-cultural and background variables impact performance on neuropsychological measures. Therefore, clinicians need to consider a child’s cultural background when evaluating performance on neuropsychological assessments. The results also indicate that future cross-cultural studies are needed to further examine the underlying cultural factors that influence neurocognitive performance. (JINS, 2017, 23, 367–380)