<![CDATA[Developments in digital technology have increased ease of access to information, but also require adolescents to have the ability to evaluate the credibility of information. This ability is related to epistemic trust, which is an individual's tendency to assess, trust, and use information based on the level of trust in its source. This study aims to develop and test the validity of a measurement tool for epistemic trust in high school adolescents in Indonesia. The study used an instrument development method with a purposive sampling technique on 200 high school students aged 15–19. Instrument development was carried out through blueprint development, expert judgment, content validity testing using Aiken's V, pilot testing on 37 students, and construct validity testing using Confirmatory Factor Analysis (CFA) and reliability testing using Jamovi. The initial blueprint consisted of 30 items representing three dimensions: trust, mistrust, and credulity. After validation, 11 items met psychometric criteria. The CFA results showed that all items had significant coefficients (p < 0.05), with the highest factor loading value for item i21 ( = 0.741). The model fit test showed an RMSEA of 0.0775 and a SRMR of 0.0801, which fall within the acceptable fit category. However, the CFI of 0.870 and TLI of 0.829 did not meet the good fit criteria. Overall, the developed epistemic trust instrument has adequate construct validity and is suitable for measuring epistemic trust in high school adolescents in Indonesia. However, item refinement and testing on a larger sample are still needed.]]>
