The overall aim of this thesis was to investigate daily time management (DTM) and time-related interventions aiming to enhance participation in everyday activities among school-age children and young adults with neurodevelopmental disorders. I was delighted to have the opportunity to start research in this area! This thesis can contribute to knowledge about daily time management for people with neurodevelopmental disorders. I also hope that the thesis can arouse interest and inspiration in providing tools for those children, adolescents and adults with neurodevelopmental disorders who need time-related interventions. Attention-deficit/hyperactivity disorder According to DSM-5 (American Psychiatric Association, 2013), the core symptoms of ADHD are difficulties with attention or hyperactivity or a combination of the two (Faraone et al., 2015). The symptoms appear to change during the child's development, with preschool children more often having problems with hyperactivity/impulsivity than attention. Difficulties with hyperactivity/impulsivity tend to decrease over time, while difficulties with attention appear to remain relatively stable (Wahlstedt, 2009). Those children who have the combined type of ADHD are expected to experience the greatest difficulties with attention at older ages, as hyperactivity/impulsivity are expected to decrease. Intellectual disabilities According to DSM-5 (American Psychiatric Association, 2013), ID is defined as a deficit in intellectual functioning (IQ < 70) combined with a deficit in adaptive functioning in at least one of three domains: conceptual, social, and practical. The conceptual domain includes language and literacy, concepts of money, time and numbers, and self-direction. The social domain includes interpersonal skills, social responsibility and social problem-solving. The practical domain includes activities of daily living, e.g. personal care, occupational performance and use of products involved in daily activities (American Association on Intellectual and Developmental Disabilities, 2010). The global prevalence of people with ID is estimated to be about 1% and among adults about 0.5% (Maulik, Mascarenhas, Mathers, Dua, & Saxena, 2011). Maulik et al. (2011) found a higher prevalence in low-and middle-income countries, in studies that did not use standard diagnostic systems and in studies with children and adolescents compared to adults. Children with ID have slower cognitive development than children without disabilities, and the level of abstract thinking as an adult is lower (Kylén, 1986). People with ID have limitations in their executive functions (Danielsson, Henry, Ronnberg, & Nilsson, 2010). It is well known that difficulties with abstract concepts such as the understanding of time concepts (Kylén, 1986; Owen & Participation and autonomy According to ICF, participation is defined as "involvement in a life situation" (World Health Organization, 2007). Participation can be seen primarily as an interaction between the person and the environment, both social and phys...