Inclusion Criteria:  Have a diagnosis of plaque psoriasis with or without psoriatic arthritis for at least 6 months before screening A woman of childbearing potential must have a negative urine pregnancy test at screening and at baseline Agree not to receive a live virus or live bacterial vaccination during the study, or within 3 months after the last administration of study drug Agree to avoid prolonged sun exposure and avoid use of tanning booths or other ultraviolet (UV) light sources during study Must sign an informed consent form (ICF) indicating that he or she understands the purpose of, and procedures required for, the study and is willing to participate in the study  Exclusion Criteria:  Has a nonplaque form of psoriasis (example, erythrodermic, guttate, or pustular) Has a history of or current signs or symptoms of liver or renal insufficiency (estimated creatinine clearance below 60 milliliter/minute [mL/min]); significant, progressive, or uncontrolled cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, rheumatologic, psychiatric, or metabolic disturbances Currently has a or has a history of malignancy within 5 year before screening (exceptions are nonmelanoma skin cancer that has been adequately treated with no evidence of recurrence for at least 3 months before the first study drug administration and cervical carcinoma in situ that has been treated with no evidence of recurrence for at least 3 months before screening, or malignancy, which is considered cured with minimal risk of recurrence) History of, or ongoing, chronic or recurrent infectious disease, including but not limited to, recurrent sinopulmonary infections, bronchiectasis, recurrent renal/urinary tract infection (example, recurrent pyelonephritis, recurrent cystitis), fungal infection (mucocutaneous candidiasis), an open, draining, or infected skin wound, or an ulcer Has previously received guselkumab