A Study Comparing the Safety and Efficacy of Risankizumab to Methotrexate in Subjects With Moderate to Severe Plaque Psoriasis

* Have a diagnosis of plaque psoriasis (with or without concurrent psoriatic arthritis) for at least 6 months before the first administration of study drug * Have stable moderate to severe plaque psoriasis with or without psoriatic arthritis at both Screening and Baseline Visits * Be a candidate for systemic therapy for plaque psoriasis as assessed by the investigator * Be a candidate for treatment with methotrexate (MTX) according to local label

* Subjects with non-plaque forms of psoriasis, current drug-induced psoriasis, or active ongoing inflammatory diseases other than psoriasis that might confound study evaluations according to investigator's judgment * Previous exposure to risankizumab * Previous exposure to MTX * Use of any prohibited medication or any drug considered likely to interfere with the safe conduct of the study, as assessed by the investigator * Subject has a history of clinically significant hematologic, renal, or liver disease