**Study Overview**: This research aims to test how well a drug called **valbenazine** works for adults showing symptoms of **Tardive Dyskinesia (TD)**. TD is a condition where people have uncontrollable, repetitive movements, usually due to long-term medication use. The study focuses on those who still have symptoms while on or after stopping a type of medication called **VMAT2 inhibitors**, which are used to manage these movements. **Eligibility**: Participants must be at least 18 years old and have been diagnosed with conditions like schizophrenia, bipolar disorder, or major depressive disorder for at least three months before the study. They must also have mild TD for at least three months. However, those with Parkinsonism (another movement disorder), recent substance abuse issues, or certain heart or liver conditions are not eligible. **Key Points**: - The study checks the effectiveness of valbenazine on both doctor and patient observations. - Participants can be on or have stopped a VMAT2 inhibitor. - Be aware of the eligibility criteria, including specific health conditions that may exclude participation. **Note**: It's important to discuss with a healthcare provider to understand if participating in this study is right for you.