Schizophrenia is a common and severe psychiatric illness characterized by extreme disturbances of cognition and thought, affecting language, perception and sense of self. This study will assess adverse events, change in disease activity, and how oral emraclidine moves through the body in adult participants with schizophrenia Emraclidine is an investigational drug being developed for the treatment of schizophrenia. Participants are placed in one of two parts, Part A or Part B, where each group will receive a different treatment. Participants will receive either oral emraclidine or placebo. Approximately 258 participants will be enrolled across roughly 32 sites in the United States. Participants in Part A will be assigned to one of multiple ascending doses of emraclidine or placebo administered orally for 14 days or up to 21 days. Participants in Part B will receive Emraclidine or placebo administered orally for up to 42 days. Participants will be followed for 30 days after the last dose of the study drug. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects and completing questionnaires.