Vitiligo is the most common acquired pigmentary disorder encountered in dermatology clinics. It affects individuals across all ages and genders, with a particularly profound effect on those with darker skin tones. It can significantly reduce quality of life, often resulting in psychological challenges such as mental health issues and social withdrawal. The treatment is challenging due to the unpredictable course of the disease. It is therefore important to monitor the activity for appropriate treatment and to measure outcomes that matter to patients and doctors. The chapter summarizes the concept of stability and its importance in treatment and various tools to assess the outcome and quality of life in these patients.