Background: Childhood and adolescence represent a critical period for shaping long-term dietary habits, including whole grain consumption, which remains low despite well-documented health benefits. Objective: This cross-sectional study (November–December 2024) examined Slovenian adolescents’ attitudes toward whole-grain foods in the context of organized school meals. Methods: Participants aged 10–12 years and 14–19 years (N = 501; mean age 15.6 ± 2.6) completed an online questionnaire assessing knowledge, self-reported consumption frequency, preferences, motivational factors, and food neophobia using the translated Italian Child Food Neophobia Scale (ICFNS). Based on ICFNS scores, participants were classified as low (≤17), medium (18–24), or high (≥25) in food neophobia. Results: Older adolescents demonstrated better knowledge of whole-grain health benefits; however, greater knowledge was not associated with higher self-reported consumption. Food neophobia was strongly associated with lower consumption frequency and reduced willingness to try whole-grain foods, including whole-grain bread, oatmeal, buckwheat porridge and brown rice. Across all groups, taste was the most consistent motivator for trying whole-grain foods. Older adolescents prioritized health and appearance as key reasons for eating more whole grain foods. Conclusions: Findings suggest that improving taste, increasing exposure, and leveraging institutional settings such as schools, where availability, preparation, and social cues can be managed, may be effective in promoting whole-grain food consumption.