The widely spread dependence on smartphones by children, adolescents, and adults has shoved researchers to assess its impact on the wellbeing of individuals. Nomophobia, the fear of being out of cellular contact, was typically assessed by self-report measures or proxy measures in adolescents and older adults. The goal of the current study was to examine nomophobia in late childhood and adolescence using scenario-based vignettes that are interactively presented and mediated by computers. To fulfill this goal, the Interactive Electronic Nomophobia Test (IENT), comprising of five scenario-based vignettes, was developed and administered to 1211 students aged between 10 and 18 years and enrolled in grades 5–12. The IENT psychometric properties were examined using a series of confirmatory factor analysis and structural equation modeling. Additionally, the study examined the clustering nomophobia symptoms in a nationally representative sample of Omani students and explored the association of these Nomophobia symptoms with both students’ grade and gender. Results of the study provided evidence of the four-pronged structure of the IENT, and an overall all composite nomophobia score, with strong associations found among the subscales, and between each of the four subscales and Nomophobia composite score. Invariance tests found significantly different model results by gender in all cases. Finally, cluster analysis revealed two to three clusters, with significant associations between gender, class, and cluster type. Implications of the study are discussed in view of previous literature on the assessment of nomophobia and smartphone addiction.