Biomarkers can provide insights into disease pathogenesis and assist clinicians in screening patients with psoriasis for arthritis. They can also help to stratify patients who are at risk for progression to bone destruction or ankylosis. Biomarkers in psoriatic disease are still in the discovery phase, but the field is advancing at a rapid pace. This review discusses definitions of the different types of biomarkers and the development of markers that reflect preclinical and early psoriatic arthritis along with those that may be able to predict disease severity and response to anti-tumor necrosis factor agents.