The vasculitides are complex, multisystem diseases, the natural history of which has been transformed by the use of immunosuppressive therapy. In many cases, survival is characterized by the presence of ongoing low-grade disease activity and, now that patients can survive acute, life-threatening manifestations of vasculitis, the new challenge is to provide accurate descriptions of these problems so as to plan appropriate changes in therapy to ensure optimal control of disease, with minimal toxicity, damage, and impairment of function. To achieve these aims, it is necessary to undertake structured evaluation of patients, with a significant dependence on careful clinical observation, supported by appropriate laboratory investigation at all stages from diagnosis to long-term care of these patients. This chapter reviews the important aspects of disease assessment and recommends a strategy for managing these complex patients. We can make use of standardized disease assessment instruments, such as the Birmingham Vasculitis Assessment Score and the Vasculitis Damage Index, to serve as an aide memoire in documenting the clinical features of disease. Routine monitoring for drug toxicity in the short-term and long-term is essential. Above all, however, it is very important to review these patients regularly and see them urgently in case of flares or complications, which are a common problem in most forms of vasculitis.