A Study of LY3361237 in Participants With Psoriasis

Inclusion Criteria: * Have chronic plaque psoriasis for at least 6 months * Be willing and able to undergo skin biopsies * Body mass index (BMI) within the range of 18 to 40 kilograms per meter squared (kg/m²) * Female participants must agree to use birth control during the study Exclusion Criteria: * Have had certain types of infection within the last six months * Have a clinically significant active infection, or recent acute active infection within the last 30 days * Have other serious or unstable illnesses * Have a history of organ or bone marrow transplant * Have received any live vaccine within the last 4 weeks prior to screening * Have received systemic nonbiologic psoriasis therapy within 4 weeks prior to study day 1 * Have received topical psoriasis treatment within 14 days prior to study day 1 * Have excessive skin exposure or use tanning booths for at least 4 weeks prior to study day 1