Psychosis is a disabling condition that typically has its onset in adolescence and early adulthood. Many young people with psychosis have difficulty navigating services or are reluctant to engage in treatment until their illness becomes an emergency. Consequently, nearly half of all new psychotic disorders are diagnosed in the emergency department (ED). Despite the rationale and evidence for early psychosis intervention (EPI), around half of youth do not access these services. The investigators will use short message service (SMS)/text messaging, a low-cost, low-complexity, youth-friendly approach, to improve transitions in care from the ED and related acute services to EPI services, investigating the intervention's effect on attendance at the first consultation appointment, longer term service engagement, and system-level outcomes. The investigators will also evaluate cost-effectiveness and user perspectives of the intervention.