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.