While physical inactivity is a key risk factor for a range of chronic diseases and conditions associated with aging, a significant proportion of midlife and older adults remain insufficiently active. This is particularly true for ethnic minority populations such as Latino adults for whom few culturally adapted programs have been developed and tested. The major objective of this 12-month cluster-randomized controlled trial is to test the comparative effectiveness of two linguistically and culturally adapted, community-based physical activity interventions with the potential for broad reach and translation. Ten local community centers serving a sizable number of Latino residents were randomized to receive one of two physical activity interventions. The Virtual Advisor program employs a computer-based embodied conversational agent named “Carmen” to deliver interactive, individually tailored physical activity advice and support. A similar intervention program is delivered by trained Peer Advisors. The target population consists of generally healthy, insufficiently active Latino adults ages 50 years and older living within proximity to a designated community center. The major outcomes are changes in walking and other forms of physical activity measured via self-report and accelerometry. Secondary outcomes include physical function and well-being variables. In addition to these outcome analyses, comparative cost analysis of the two programs, potential mediators of intervention success, and baseline moderators of intervention effects will be explored to better determine which subgroups do best with which type of intervention. Here we present the study design and methods, including recruitment strategies and yield as well as study baseline characteristics. Trial Registration: clinicaltrial.gov Identifier = NCT02111213.

Physical inactivity is a key risk factor for a range of chronic diseases and conditions, yet, approximately 50% of U.S. adults fall below recommended levels of regular aerobic physical activity (PA). This is particularly true for ethnic minority populations such as Latino adults for whom few culturally adapted programs have been developed and tested. Text messaging (SMS) represents a convenient and accessible communication channel for delivering targeted PA information and support, but has not been rigorously evaluated against standard telehealth advising programs. The objective of the On The Move randomized controlled trial is to test the effectiveness of a linguistically and culturally targeted SMS PA intervention (SMS PA Advisor) versus two comparison conditions: a) a standard, staff-delivered phone PA intervention (Telephone PA Advisor) and b) an attentioncontrol arm consisting of a culturally targeted SMS intervention to promote a healthy diet (SMS Nutrition Advisor). The study sample (N = 350) consists of generally healthy, insufficiently active Latino adults ages 35 years and older living in five northern California counties. Study assessments occur at baseline, 6, and 12 months, with a subset of participants completing 18-month assessments. The primary outcome is 12-month change in walking, and secondary outcomes include other forms of PA, assessed via validated self-report measures and supported by accelerometry, and physical function and well-being variables. Potential mediators and moderators of intervention success will be explored to better determine which subgroups do best with which type of intervention. Here we present the study design and methods, including recruitment strategies and yields. Trial Registration: clinicaltrial.gov Identifier = NCT02385591

Highlights: Optimizing Latinos’ health and well-being is a crucial preventive medicine effort. Understanding group differences can inform future research and public health efforts. Latinos vs non-Latinos differed in physical health, stress, and religiosity. Matched Latinos samples also differed significantly in four well-being domains. Our methods offer guidance for examining multi-ethnic differences in well-being.