The study will demonstrate how delivery of text messages for appointment reminders and motivational/coaching message to justice-involved youth and their caregivers will lead to greater youth substance use treatment attendance and engagement. The study will start with identifying the feasibility and acceptability of the SMS text-messaging intervention with community-supervised justice-involved youth. Then, the study will determine whether the tailored dyadic (youth and caregiver) SMS text-messaging intervention improves justice-involved youth substance use or dual diagnosis treatment attendance and engagement relative to standard of care (not receiving text messaging appointment reminders and motivational/coaching messages). Finally, the study will characterize patterns of key justice and behavioral health system-level factors that promote or hinder eventual adoption and sustainability of mHealth technology as a tool to improve treatment attendance for justice-involved youth.