The purpose of the study is to assess how well each dose of lumateperone (Dose 1 and 2) works when given alone as compared to placebo in participants with major depressive disorder (MDD; a medical condition characterized by a persistent feeling of deep sadness, hopelessness, and a loss of interest in activities for a prolonged period of time and interfere with ability to function).
Medically stable based on physical examination, medical history, vital signs, and 12-lead electrocardiogram (ECG) performed at screening and where applicable at DB period baseline
Medically stable based on clinical laboratory tests performed at screening and where applicable at DB period baseline
Meets the Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) diagnostic criteria for recurrent or single episode MDD, without psychotic features, based upon clinical assessment and confirmed by Structured Clinical Interview for DSM-5 Axis I Disorders - Clinical Trials Version (SCID-CT)
Has moderate-to-severe depression as measured by a rater-administered MADRS total greater than or equal to (>=) 26 score and corresponding to a CGI-S score of >=4 at screening and DB baseline
The participant experiences a >=25 percent (%) decrease in the MADRS total score between screening and DB baseline
The participant experiences a >=25% decrease in the QIDS-SR-16 total score between screening and DB baseline
Has homicidal ideation/intent, per the investigator's clinical judgment, or has suicidal ideation with some intent to act within 3 months prior to the start of the screening period, per the investigator's clinical judgment or based on the Columbia-Suicide Severity Rating Scale (C-SSRS), corresponding to a response of "Yes" on Item 4 (active suicidal ideation with some intent to act, without specific plan) or Item 5 (active suicidal ideation with specific plan and intent) for suicidal ideation on the C-SSRS, or a history of suicidal behavior within the past 6 months prior to the start of the screening period
Has a history of moderate-to-severe substance use disorder including alcohol use disorder according to DSM-5 criteria within 6 months before screening