Conclusions
This mixed methods study generated novel understandings about how youth with co‐occurring conditions develop competencies related to self‐care, self‐advocacy and self‐management in preparation for paediatric–adult service transitions. Results demonstrated the assessment of transition readiness using a generic scale does not address the nuanced and complex needs of youth with co‐occurring chronic health and mental health conditions. Our findings suggest tailoring transition readiness practices for this group based on youths' own goals, symptoms, coping mechanisms and resources.