Children and adolescents treated with antipsychotic drugs can experience severe and bothersome adverse drug reactions (ADRs), which can have a physical as well as an emotional impact on their lives. It is important to monitor these children and adolescents closely so that ADRs are identified early. The aim of this thesis was to assess the daily clinical practice of monitoring for ADRs of antipsychotic drugs in children and adolescents, including the facilitators for and barriers to monitoring. First, the need for monitoring was assessed. The frequencies of spontaneously reported ADRs in children and adolescents treated with antipsychotic drugs were determined using data from the worldwide database VigiBase. Many different ADRs were reported by young people and healthcare professionals, including weight gain, breast enlargement, and movement disorders. Second, monitoring in daily clinical practice was examined. How ADRs were monitored was studied in various ways: questionnaires were completed by Dutch child and adolescent psychiatrists, medical records of an organization for child and adolescent psychiatry were examined, and prescription data from British general practitioners were analyzed. In none of these studies monitoring was optimal. The monitoring frequencies as well as what was monitored varied between healthcare professionals. Healthcare professionals rarely reported the reason for not monitoring and guidelines were most often not completely followed. Third, the support provided during antipsychotic drug treatment was assessed. There are clinical guidelines available for healthcare professionals on how to monitor for ADRs. The clarity of presentation and the applicability of ADR-related monitoring instructions in six clinical practice guidelines for children and adolescents treated with antipsychotic drugs were assessed. These guidelines were clearly presented but differed in what and how often to monitor and were not always easily applicable in daily practice. Given the ADRs that might occur, not only the healthcare professionals need support on how to monitor, but also the children, adolescents, parents, and caregivers should be provided with clear instructions and information. Therefore, adolescents treated with antipsychotic drugs were interviewed and asked about their experiences, needs, preferences, and suggestions for improvement. The preliminary results emphasized the importance of personal guidance and involvement in decision-making. Better monitoring is of importance so ADRs can be detected early and the antipsychotic drug treatment can be adjusted according to the individual needs and preferences of the child or adolescent, ensuring a safe and effective antipsychotic drug treatment for this vulnerable population.