The objective of this multi scientific research is to explore, develop, evaluate, and implement different models of Hospital Based Home Care (HBHC) for children with long-term illness (LTI) and their families. Four studies are used: (I) children with HIV, (II) cancer, (III) preterm birth and (IV) diabetes. The research is based on the child´s and the family´s needs and on an integrative synthesis of previous and ongoing research. By addressing four interrelated fields, we will reconsider, in a comparative study (V) how HBHC can be developed from nursing, psychosocial, economic, gender and cultural perspectives to a theoretic model for handling contextual complexity in implementation processes. The research follows a framework for developing complex interventions in health care and includes a child/family centered care approach. Interactive and interdisciplinary designs are used to involve children, parents, and professionals in the process. The research is planned in close co-operation with care practice and includes both qualitative and quantitative methods, including RCTs, controlled studies, and ethnographic fieldworks. Our research will increase the knowledge of context and culture that endure respectively obstruct implementation processes in general, and more specifically on how to implement HCBC for children with LTI, and thereby reduce the costs of hospital-based health care, and increase the psychosocial benefits due to reduced hospitalisations for children.