Patients with asthma commonly have other medical problems, such as obesity, but it is unclear if obesity independently relates to asthma occurrence. Young and colleagues examined the association between asthma and obesity from January 1997 to December 1998 in this population-based prevalence case-control study of TRICARE region 11, a military managed care program encompassing Washington, Oregon, and northern Idaho. They compared 2788 patients with asthma and 39 637 controls, using logistic regression to estimate associations between asthma and body mass index (BMI), and variables such as demographics, lifestyle, and comorbid risk factors. They included a similar comparison in a verified substudy on the use of asthma medications. The results show that BMI, age, sex, beneficiary status, and arthritis are significant independent predictors of asthma prevalence in both the larger analysis and the verified substudy. Stomach ulcer, depression, hypertension, and white race were also independent predictors of asthma prevalence in the larger analysis.