The aim of this study was to explore student loneliness and a lack of sense of belonging in Swedish schools, and to gain insight from school staff on how to identify and address these issues. Fourteen school personnel—including counsellors, special educators, and teachers—were interviewed using a semi-structured approach. The data were analysed thematically, both inductively and deductively. According to the staff, loneliness and lack of belonging are widespread phenomena, observable throughout the school day—for example, during breaks and other social interactions. These are complex phenomena influenced by both individual and environmental factors. Contributing elements to students’ school experiences were identified within the educational, physical, and social aspects of schooling. In particular staff highlighted how these aspects intertwine and may negatively affect students’ feelings of isolation and alienation. Key implications include the need for school leaders and policy makers to consider the interconnectedness of these dimensions—the educational, physical, and social aspects of schooling—in order to effectively address loneliness and foster more inclusive and supportive school environments for all students.