This is a Phase 4, international, multicenter, randomized, double-blind, placebo-controlled study examining the effect of risankizumab in subjects with moderate to severe genital psoriasis (Study G) or moderate to severe scalp psoriasis (Study-S). Eligible subjects within each study will be randomized to receive risankizumab or placebo in a 1:1 ratio. Subjects who meet the criteria for both Study-G and Study-S will first be randomized to either Study G or Study-S with equal probability and then will be randomized to receive either risankizumab or placebo in a 1:1 ratio. The duration of the studies will be approximately 64 weeks. Each study comprises a 30-day Screening Period, a 16-week double-blind placebo-controlled treatment period (Period A), a 36-week open-label treatment period (Period B), and an 8-week Follow-up Period.