Outcome Measures in Rheumatology (OMERACT) conferences have developed a process by which outcome measures to be included in clinical trials are identified by consensus. During OMERACT 7, held in Asilomar, CA, USA, in May 2004, a workshop on outcome measures in psoriatic arthritis was held. Information derived through a previous Delphi exercise and nominal group process was shared with the participants, as were the results from a study using completed clinical trials with biological therapies. On the basis of the evidence presented and discussions in breakout groups at the OMERACT conference, a set of domains to be included in clinical trials in psoriatic arthritis was developed and a research agenda for further studies in psoriatic arthritis proposed.