IntroductionThe Comprehensive Test of Nonverbal Intelligence-2 (CTONI-2) assesses nonverbal intelligence from ages 6–90 with 6 subtests divided into a Pictorial composite and a Geometric composite. There was no previously validated Turkish version. The purpose of this study was to adapt the CTONI-2 for Turkish primary-school children aged 8–10 and to test its reliability and validity, while it was also applied to a small pilot sample of secondary-school children (N = 54) to examine performance levels on subtests and preliminary group differences by gender, grade level, and age.MethodsThe participants of the adaptation study were 590 primary-school students in Turkey. Internal-structure evidence was examined using CFA, and convergent validity was examined through correlations with Raven's Standard Progressive Matrices. KR-20 and test-retest techniques were employed to assess reliability. All six subtests were then administered to the pilot secondary-school sample. Patterns of performance were explored using independent-samples t-tests, one-way ANOVAs, and Pearson correlations, with raw-score percentages used only for exploratory descriptive interpretation.ResultsCFA results showed a unidimensional structure with CFI = 0.95, RMSEA = 0.07 and CR = 0.78. KR-20 ranged from 0.79 to 0.94; test-retest from 0.81 to 0.96. The pilot application scores were between 64 and 72% of maximum score per subtest, with all means in the Average-to-Above-Average range. There were no significant differences between males and females. Grade 10 students performed better than Grade 11 students on Geometric Analogies (d = 0.83), and age was negatively correlated with geometric reasoning subtests (r = −0.28 to −0.33).DiscussionGiven the small and unevenly distributed pilot sample, these findings should be interpreted cautiously. The results support the reliability and validity of the Turkish CTONI-2 in the primary-school adaptation sample and provide preliminary application evidence for secondary-school students.