Asthma is a common condition met with in pulmonology outpatient practice. The approach to uncontrolled asthma includes elimination of the various possible mimics of the condition, attention to comorbidities and inhaler technique, elimination of potential triggers in the environment and consideration of a possible lack of adherence to treatment. When all else fails, phenotyping the disease is important for institution of biologic therapy. This chapter outlines a systematic approach to the diagnosis of uncontrolled asthma.