Purpose: To describe the incidence of and risk factors for impaired cognitive function in intensive care unit (ICU) survivors. We hypothesized that age, severity of illness, and days in coma, delirium, mechanical ventilation in the ICU would be associated with impaired cognitive function. Methods: We included all adults, alive 6 months after acute admission to one of the 24 Danish ICUs participating in the AID-ICU cohort study. Trained professionals assessed cognitive function in patients’ homes or in outpatient clinics using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) 6 months after ICU admission. Potential risk factors for cognitive impairment were analyzed with linear regression models. Results: In total, 237 ICU patients were alive 6 months after ICU admission and did not meet the exclusion criteria. A total of 106 patients completed the cognitive assessment. The median RBANS global cognitive score was 76 (interquartile range, 62-91), and 52% had a global cognitive score 1.5 SD below the normative mean and 36% displayed a global cognitive score 2 SD below the normative mean, similar to that of Alzheimer's disease. Higher age was associated with poorer RBANS global cognitive score (estimate −0.35 [95% confidence interval −0.63 to −0.07] per year). Conclusions: In this multicenter study of adult ICU survivors, cognitive impairment was frequent and severe in those assessed at 6 months. Higher age was a risk factor for cognitive impairment, but events related to the ICU stay were not associated with poorer cognitive performance at 6 months.