This study explores the factors contributing to the imbalance between fiction and nonfiction materials in primary school classrooms, with a specific emphasis on the perspectives of prospective teachers. Employing a qualitative research approach, the investigation involved 30 student teachers who had completed the Children’s Literature course at a Spanish university. Semi-structured interviews, with questions validated by expert judges, were utilized to gather responses, which were subsequently transcribed and analyzed through coding, following a categorical framework refined post-response analysis. The primary findings indicate a restricted exposure to nonfiction picturebooks in familial and educational settings. Despite positive emotional responses from trainee teachers, the study reveals an inadequacy in their training, hindering the development of a comprehensive understanding and the reinforcement of self-efficacy for integrating nonfiction materials into future teaching practices. Furthermore, the research underscores a disparity between the perceived significance of nonfiction picturebooks for enhancing children’s multimodal reading and the inclination of trainee teachers to prioritize fiction due to a lack of confidence and previous exposure. As a result, the study proposes a reassessment of teacher training programs, recommending a more thorough focus on nonfiction materials and continuous professional development to address the disparity between beliefs and actual classroom practices.