Aim. This paper is a report of a Neuman systems model-guided study of the effects of nurse-facilitated family participation in psychological care on the extent of patient delirium and psychological recovery following critical illness.Background. Psychological disturbances resulting from critical illness have been well documented in international literature. Few studies have tested interventions designed to alleviate such disturbances.Methods. A comparative time series design was used. A total of 170 critically ill patients and families participated in the study – 83 in the control group and 87 in the intervention group. Data were collected during critical illness and subsequent recovery using the Therapeutic Intervention Scoring System-28, Intensive Care Delirium Screening Checklist and the Sickness Impact Profile. The study was carried out in Northern Ireland, data collection taking place from January 2004 to December 2005.Results/findings. Nurse-facilitated family participation in psychological care did not significantly reduce the incidence of delirium among patients in critical care, but patients receiving intervention demonstrated better psychological recovery and wellbeing than the control group at 4, 8 and 12 weeks after admission to critical care.Conclusion. Nurse-facilitated family participation in the psychological care may strengthen the lines of defence and resistance against the stressors experienced by the patient during critical illness and improve psychological recovery.