The assessment of asthma control is pivotal to the evaluation of treatment response in individuals and in clinical trials. Previously, asthma control, severity, and exacerbations were defined and assessed in many different ways. The Task Force was established to provide recommendations about standardization of outcomes relating to asthma control, severity, and exacerbations in clinical trials and clinical practice, for adults and children aged 6 years or older. A narrative literature review was conducted to evaluate the measurement properties and strengths/weaknesses of outcome measures relevant to asthma control and exacerbations. The review focused on diary variables, physiologic measurements, composite scores, biomarkers, quality of life questionnaires, and indirect measures. The Task Force developed new definitions for asthma control, severity, and exacerbations, based on current treatment principles and clinical and research relevance. In view of current knowledge about the multiple domains of asthma and asthma control, no single outcome measure can adequately assess asthma control. Its assessment in clinical trials and in clinical practice should include components relevant to both of the goals of asthma treatment, namely achievement of best possible clinical control and reduction of future risk of adverse outcomes. Recommendations are provided for the assessment of asthma control in clinical trials and clinical practice, both at baseline and in the assessment of treatment response. The Task Force recommendations provide a basis for a multicomponent assessment of asthma by clinicians, researchers, and other relevant groups in the design, conduct, and evaluation of clinical trials, and in clinical practice.