Outcome assessment in rheumatic disorders is getting more and more attention. A series of Outcome Measures in Rheumatology (OMERACT) conferences has provided a good impulse for further research in the field. In this chapter we will review the results of the last OMERACT 4 conference in detail. This conference was focused on longitudinal/observational studies, rheumatoid arthritis (response criteria and imaging), and core sets for ankylosing spondylitis and systemic lupus erythematosus. Moreover, an overview of recent literature on measures of disease activity, quality of life measures, and imaging is presented. For the various rheumatic disorders, several new instruments and/or further validation steps are described.