Asthma is a chronic inflammatory disease that affects an estimated 25 million people in the United States. In 70% to 90% of cases, asthma is associated with IgE-mediated mechanisms, which have proved central to allergen-induced inflammation in preclinical and clinical models. The importance of IgE levels in patients with moderate to severe asthma has been confirmed in randomized controlled studies with a targeted IgE blocker. Advances in laboratory methods to detect and quantify allergen-specific IgE antibodies have allowed for a quick-and-easy diagnosis of allergic IgE-mediated sensitivities in the office. Pulmonologists tend to order in vitro tests to measure allergen-specific IgE rather than to perform allergen skin testing, which is seen as the purview of allergists. This article reviews the importance of allergen testing in patients with asthma-whether by skin testing or by in vitro methods-and highlights the advantages, limitations, and interpretation of results derived from each method. Additionally, this article includes suggested documentation and administrative details for physician reporting in the office setting.