Biomarkers can provide valuable insights into disease susceptibility and natural history and may serve as surrogate endpoints for a variety of different outcomes. At the 2008 annual meeting of GRAPPA (Group for Research and Assessment of Psoriasis and Psoriatic Arthritis), members were updated on the development of biomarkers in psoriatic arthritis (PsA). Plenary presentations included a translational approach to biomarker development (Christopher Ritchlin, University of Rochester, NY, USA), biomarkers for psoriasis (Abrar Qureshi, Harvard Medical School, MA, USA), new data on biomarkers for damage in PsA (Kurt de Vlam, University Hospitals Leuven, Belgium), and design considerations for a longitudinal study of joint damage being undertaken under the OMERACT umbrella with colleagues working on rheumatoid arthritis and ankylosing spondylitis (Costantino Pitzalis, Barts and the London School of Medicine, London, UK; Oliver FitzGerald, St. Vincent’s Hospital, Dublin, Ireland). At the conclusion of this session, the meeting attendees discussed specific design issues of the proposed longitudinal study, including study duration, disease process core domains, and the instruments to be used in recording enthesitis, dactylitis, nail involvement, quality of life and structural damage. The appearance of new therapeutic options in PsA raises the need for sensitive biomarkers for both disease activity and outcome.