Objective: To develop a youth form of the Motivators of and Barriers to Health-Smart Behaviors Inventory (MB-HSBI--Youth) for use in identifying self-reported motivators of and barriers to the following health-promoting behaviors (called "health-smart" behaviors): eating a healthy breakfast, eating healthy foods and snacks, drinking healthy drinks, and engaging in physical activity. Design: The MB-HSBI--Youth was developed through several research phases as part of a larger, multisite, and multicomponent study on modifying and preventing obesity in families. A critical aspect of the larger study was to identify the motivators of and barriers to the above-identified health-smart behaviors among African American, Asian American, Hispanic/Latino American, and non-Hispanic White American adults and youth. After preliminary research involving content validity, item analyses, and pilot testing, a pilot version of the MB-HSBI--Youth was administered to a national sample of 567 culturally diverse youth ranging from 9 to 17 years old. Results: Factor analyses and internal consistency results revealed the existence of multiple subscales measuring motivators of and barriers to each of the above-specified health-smart behaviors. Scores on the MB-HSBI--Youth correlated in expected directions with health self-efficacy scores and with ratings of the importance of health-related behavioral goals. Conclusion: The MB-HSBI--Youth may be a useful and novel tool for developing assessment-based, culturally sensitive health promotion programs customized to be responsive to the motivators of and barriers to health-smart behaviors identified in target communities, particularly those communities whose members are mostly racial/ethnic minorities. (Contains 5 tables and 2 footnotes.)