Advancements in critical care medicine result in a growing population of survivors of critical illness. Many intensive care unit (ICU) patients have physical, mental and cognitive sequelae after discharge from the ICU, known as post-intensive care syndrome (PICS). These problems are associated with long-lasting restrictions in daily functioning and reduced health-related quality of life (QoL), and can also negatively affect family members (PICS-F). The nature of these restrictions require interdisciplinary rehabilitation care, but to date there is no structured pathway for the prevention and treatment of the symptoms of PICS. The aim of this thesis was to explore the course and prognosis of functioning in ICU survivors, and to investigate means for early identification of PICS. In the studies assembled in this thesis, we found that patients with prolonged ICU-stay, longer duration of mechanical ventilation (> 48 hours), and/or ICU-AW, have a higher risk of short- and long-term functional impairments, limitations in activities and restrictions in participation. A majority of ICU survivors do not receive adequate rehabilitation care after discharge from the hospital. This implies, that patients and their close relatives should be closely monitored after discharge from the ICU to initiate interdisciplinary rehabilitation treatment. In order to improve the quality of survivorship, we propose a structured, stepped care rehabilitation pathway, consisting of clinical assessments with validated screening instruments, interdisciplinary rehabilitation interventions, tailored to the patients’ abilities and needs, and adequate handover in the transition of care.