We determined that the seven facilities we inspected were generally following U.S. Immigration and Customs Enforcement (ICE) guidance for documenting decisions on segregating detainees with mental health conditions and promptly reporting segregation placement information for detainees with mental health conditions to ICE field offices. However, the field offices we reviewed did not record and promptly report all instances of segregation to ICE headquarters, nor did their system properly reflect all required reviews of ongoing segregation cases. Also, ICE does not regularly compare segregation data in the electronic management system with information at detention facilities to assess the accuracy and reliability of data in the system. Unless ICE field offices comply with requirements to report and record these reviews, ICE headquarters cannot be sure required reviews are taking place and may not have all the information needed to assess the use of segregation, which could put detainees and facility staff at risk of harm. We made three recommendations to ICE to improve oversight and accountability for segregation of detainees with mental health conditions.