There are some individuals with severe and persistent mental illnesses who cannot be managed by primary and secondary services and who require tertiary care. Such clients are characterized by aggressiveness, noncompliance with medication, and dangerousness. Tertiary care program elements include psychosocial rehabilitation, sophisticated medication management, and behavioural approaches. Tertiary care may be delivered through assertive community treatment and/or specialized outreach teams, community residential programs, or hospital-based services. Increasingly, organized systems have been developed to ensure that individuals meet criteria for tertiary care and receive the most appropriate level of care. Most importantly, the delivery of tertiary care must not be tied to particular settings or time frames, and level of care must be delinked from model or location of care in order to create flexible, efficient, effective mental health services.