For the estimated 14.5 million diagnosed prevalent cases of asthma in the United States, there are multiple prescription therapies that are available for treating the associated symptoms. The National Heart, Lung, and Blood Institute (NHLBI) guidelines recommend a step-up treatment paradigm that begins with short-acting beta2 agonists [SABAs] for use as needed (i.e., rescue therapy) in patients with mild disease. Patients with moderate persistent asthma should receive maintenance therapies in addition to rescue medications. Maintenance therapies include inhaled corticosteroids [ICSs], the mainstay of treatment, long-acting beta2 agonist [LABA] /ICSs, and leukotriene antagonists; patients with severe asthma receive combination therapy. Using national patient-level claims data, this report analyzes physician adherence to the treatment guidelines by exploring the use of key therapies in the newly diagnosed and recently treated asthma patient populations. Considering newly diagnosed patients, the report provides a quantitative analysis of treatment patterns and share by line of therapy, as well as progression between lines, duration of treatment on each line, and use of concomitant treatment. With respect to recently treated patients, the report quantifies a drug’s source of business compared with its competitors and details which drugs precede others through an analysis of add-versus-switch patterns. Additional analyses explore persistency and compliance by brand.