Airway changes related to childhood asthma occur early in the disease process. This pilot study focuses on the validation of the Breathmobile Case Identification Survey (BCIS) in preschool-age children in Orange County, CA. Fifty-two children from low-income Spanish-speaking families participated in the study. Thirteen children were identified as possibly having asthma from the survey results compared with 20 children diagnosed by an asthma specialist. We found that the complete seven-question survey had a sensitivity of 0.65 and a specificity of 0.94. An abbreviated three-question version had a sensitivity of 0.70 and a specificity of 0.84. Our data suggest that the abbreviated BCIS, which is simple and easily analyzed, may be a useful tool in identifying young children who are at risk for asthma and need further evaluation and appropriate therapy.