The purpose of this study is to evaluate the efficacy, safety, and tolerability of NBI-98854 administered once daily for the treatment of Tardive Dyskinesia (TD) symptoms.

This is a Phase 3, randomized, double-blind, placebo-controlled, parallel, fixed-dose study to evaluate the efficacy, safety, and tolerability of two doses of NBI-98854 (40 mg and 80 mg) compared to placebo, administered once daily. The study design includes a double-blind, placebo-controlled treatment period for 6 weeks and a double-blind NBI-98854 treatment period for an additional 42 weeks, for a total of 48 weeks of treatment. Final follow-up assessments will be conducted 4 weeks after the last dose of the study drug.

Inclusion Criteria:

1. Subjects of childbearing potential must agree to use hormonal or two forms of nonhormonal contraception (dual contraception) consistently during the screening, treatment and follow-up periods of the study.
2. Female subjects must not be pregnant.
3. Have one of the following clinical diagnoses for at least 3 months prior to screening: Schizophrenia or Schizoaffective Disorder, or Mood Disorder.
4. Have a clinical diagnosis of neuroleptic-induced TD for at least 3 months prior to screening.
5. Have moderate or severe TD.
6. If using maintenance medication(s) for schizophrenia or schizoaffective disorder, or mood disorder, be on stable doses.
7. Be in good general health.
8. Have adequate hearing, vision, and language skills to perform the procedures specified in the protocol.
9. Have a negative drug screen for amphetamines,barbiturates, benzodiazepines, phencyclidine, cocaine, opiates, or cannabinoids

Exclusion Criteria:

1. Have an active, clinically significant unstable medical condition within 1 month prior to screening.
2. Have a known history of substance dependence, or substance (drug) or alcohol abuse
3. Have a significant risk of suicidal or violent behavior.
4. Have a known history of neuroleptic malignant syndrome.
5. Have a known history of long QT syndrome or cardiac tachy-arrhythmia.
6. Have a cancer diagnosis within 3 years of screening (some exceptions allowed)
7. Have received an investigational drug within 30 days prior to screening or plan to use an investigational drug (other than NBI-98854) during the study.
8. Have a blood loss ≥550 mL or donated blood within 30 days prior to Baseline.
9. Have an allergy, hypersensitivity, or intolerance to tetrabenazine.
10. Have had previous exposure with NBI-98854 or had previously participated in an NBI-98854 clinical study.
11. Are currently pregnant or breastfeeding.