UNLABELLED: Avoidant/Restrictive Food Intake Disorder (ARFID) is defined by limited volume or variety of food intake motivated by the sensory properties of food, fear of aversive consequences, or lack of interest in food or eating associated with medical, nutritional, and psychosocial impairment. Currently, two of the most widely validated measures are The Eating Disturbances in Youth-Questionnaire (EDY-Q) and the Nine Item ARFID Screen (NIAS). The latter has proven valid and reliable for assessing this disorder. OBJECTIVE: To validate a culturally sensitive adaptation of the NIAS instrument and evaluate its psychometric properties in Mexican youths. METHOD: The sample consisted of 800 participants aged 12-30 (M = 18.56, SD = 3.52) from Mexico City and Hidalgo public educational institutions. RESULTS: The S-NIAS obtained a Cronbach's alpha of 0.84, adequate construct validity adjustment rates: CMIN = 1.88; GFI = 0.97; AGFI = 0.94; CFI = 0.98; RMR = 0.050; and RMSEA = 0.047. Measurement invariance by gender, age, and survey administration which show that construct is understood in the same way across both groups and despite the change from paper-and-pencil to online survey administration. CONCLUSION: The psychometric properties of the Spanish Nine Item ARFID Screen (S-NIAS) indicate that it is a valid and reliable instrument for evaluating symptoms associated with ARFID in this sample of youths. PUBLIC SIGNIFICANCE: Although there are advances in studying ARFID, their epidemiological data comes mainly from a few countries. Furthermore, these data are scarcer due to the lack of validated screening and assessment instruments available in a variety of world languages; having instruments for the evaluation of ARFID symptoms is essential because it could function as an auxiliary means for the detection and prevention of people at risk.