Some participants may continue into the testing session on the same day as the screening session; others will participate in the testing session at a second study visit within 4 weeks after study screening. At the start of the testing session, participants will be asked to complete a questionnaire about demographics, history of airway disease and previous skin testing, and current medication use. For participants whose testing session occurs on a different day than the screening session, vital signs measurement and PEF readings will occur and premenopausal women will have urine collected. Blood collection will occur prior to the skin test. Intradermal skin testing will consist of injections on the participant's back with multiple doses of 3 different extracts of German cockroach allergen. Each of the 3 extracts will require 4 to 7 injections, depending on the response to each dose. Erythema skin response to the dilutions will be recorded. Participants will be observed for at least 1 hour after the intradermal skin testing as a safety precaution. After the observation period, participants will undergo additional PEF testing and will be assessed for adverse reactions to the skin testing procedure. Participants may be given antihistamines to relieve itching.