The market for health applications, or apps, on mobile devices is growing rapidly, with over 40,000 currently in use. One type of app technology--clinical management apps--enable patients and providers to work together to manage chronic conditions, particularly diabetes and asthma. These apps are mostly used by health plans and large health care organizations with an interest in improving outcomes and controlling costs. Challenges to broader adoption of apps include the lack of objective research to evaluate outcomes, uncertainty about how to pay for and encourage the use of cost-effective apps, and the absence of a regulatory framework that standardizes development to ensure performance. If this infrastructure is developed, apps may serve as a catalyst to stimulate the transformation of health care generally and target low-income populations to expand access to care and help reduce health disparities.