Consider first that it may not be a good goal for her to leave the safe environment provided by her parents even to move to a residential setting. Such a change may be more stressful than helpful, and you do not want to talk her into doing something that may not be right for her (since she has trouble saying “no”). Instead, it is helpful first to assess her stage of change: does she really want to not use drugs? I would find out why this is an important goal, and how it relates to making HER happy and proud (not just pleasing you). If it is her goal, then it will be hard work to develop the skills she needs to succeed, but I would tell her that you believe in her and can help her. Then, I would practice skills training with her and role play opportunities for her to learn to say “no” to specific people who offer drugs, starting with someone who is easier to refuse, and then going from there. Build on strengths she already has to say “no”: e.g., How would you say no if someone asked you to help them commit a crime? For more information, see Implementation Guide: Skill-Building Interventions for Individuals with Serious Mental Illness (SMI) and Co-occurring Substance Use Disorders.