development and implementation, there is little evidence of the differential effects of these programs according to diversity subgroups. As a result, money and time are spent without knowing when a common format would suffice, or when a variety of targeted or even tailored interventions would be more appropriate. Given the likely growth in diversity, there is an urgent need now to enhance our current understanding of the dynamics of health communication to achieve the greatest impact for the most people.

This volume is the product of the Committee on Communication for Behavior Change in the 21st Century: Improving the Health of Diverse Populations, established by the Institute of Medicine in 1999. It focuses on those programs that involve some use of communication technology and have incorporated the transmission or exchange of messages within interventions designed to influence behavior to improve health. Programs exclusively involving interpersonal communication, such as between physician and patient, were not the focus; interventions that include other elements along with communication technology are considered.

The charge to the committee was to (1) review existing theory and research applications in health communication and health behavior change, especially as they relate to culturally diverse populations, and define research areas that would benefit from expanded or new research efforts; (2) consider up to three specific examples of health communication interventions to evaluate whether and how those strategies affect culturally diverse groups; and (3) recommend how health communication strategies may be designed and implemented to help achieve sustained gains in public health across cultural groups. The committee included experts in anthropology, psychology, mental health, cancer prevention and control, health behavior change and theory, communication and the media, social marketing, and public health. In the context of this charge, the committee considered the following questions:

• Is there evidence that targeting or tailoring messages for different cultural groups makes a difference in the effect of these messages on behavior change?