Inclusion Criteria:  Participants with hepatic impairment. Participants eligible for Group 4 should be in good health. Participants eligible for Groups 1 through 3 may have medical findings consistent with their degree of hepatic dysfunction. Participants with abnormal findings considered not clinically significant by the investigator are eligible. Body mass index within the range of 18.0 to 40.0 kg/m2 (inclusive) at screening. Willingness to avoid pregnancy or fathering children.  Exclusion Criteria:  Evidence of rapidly deteriorating hepatic function. Participants with serum calcium and phosphorus levels over the upper limits of the institutional normal ranges. History or current diagnosis of uncontrolled or significant cardiac disease indicating significant risk of safety for participation in the study, including any of the following: Participants who have a current, functioning organ transplant or have a scheduled organ transplant in the next 6 weeks from check-in. History of malignancy within 5 years of screening, with the exception of cured basal cell carcinoma, squamous cell carcinoma of the skin, ductal carcinoma in situ, or Gleason 6 prostate cancer. History of clinically significant gastrointestinal disease or surgery (cholecystectomy and appendectomy are allowed) that could impact the absorption of study drug. Participants with severe ascites or an encephalopathy ≥ Grade 2. Any major surgery within 4 weeks of screening. Donation of blood to a blood bank within 4 weeks of screening (within 2 weeks for plasma only). Blood transfusion within 4 weeks of check-in. Current or recent history (within 30 days before screening) of a clinically significant bacterial, fungal, parasitic, or mycobacterial infection, or currently receiving systemic antibiotics. Current clinically significant viral infection at screening or check-in. Positive serology for hepatitis B virus (eg, hepatitis B surface antigen) or human immunodeficiency virus. Participants whose results are compatible with immunity due to infection or prior immunization for hepatitis B may be included at the discretion of the investigator. History of alcoholism within 3 months of screening. Positive breath test for ethanol or positive urine screen for drugs of abuse that is not otherwise explained by permitted concomitant medications. Current treatment or treatment within 30 days or 5 half-lives (whichever is longer) of study drug administration with another investigational medication or current enrollment in another investigational drug protocol. Current treatment or treatment within 30 days or 5 half-lives (whichever is longer) of study drug administration with strong or moderate inducer or potent inhibitor of CYP3A4. Receipt of live (including attenuated) vaccines or anticipation of need for such a vaccine during the study. (Note: Non-live or inactivated vaccines allowed up to 2 weeks before first dose administration.) Known hypersensitivity or severe reaction to parsaclisib or excipients of parsaclisib. History of any significant drug allergy (such as anaphylaxis or hepatotoxicity) deemed clinically relevant by the investigator. Inability to be venipunctured or tolerate venous access. Participants eligible for Group 4 who have a history or presence of liver disease or liver injury as indicated by an abnormal clinically significant liver function profile at screening or check-in. Participants eligible for Group 4 who have a positive test for hepatitis C virus. Participants eligible for Group 4 who used tobacco- or nicotine-containing products within 6 months of screening. Women who are pregnant or breastfeeding