ABSTRACT/PROJECT SUMMARY Overweight/obesity rates continue to surge, with severity of weight increasing and no age group spared. Fueling this epidemic are intergenerational links reflecting an interplay of genetic, physiological, behavioral and environmental factors. Parental obesity, particularly maternal severe obesity, is a potent predictor of obesity in child offspring. Parents are the primary influence on the development of pediatric lifestyle behaviors, acting as gatekeepers of the home food environment (HFE) and shaping eating behaviors via parenting practices and modelling, all key drivers in childhood obesity prevention and development. For millions of families, the cycle of obesity will continue without new discoveries and innovative solutions targeting youth at highest risk to slow these intergenerational trends. Metabolic and bariatric surgery (MBS) is the most effective treatment for severe obesity, with most patients female and approximately 40 years of age, many of whom are mothers with dependent children who already have overweight/obesity. These mothers may experience impressive weight loss and make their own significant lifestyle changes following MBS yet may not be changing the obesogenic nature of the household and diminishing the known risk to offspring. Maternal MBS may be a uniquely powerful (yet currently missed) intergenerational opportunity to effectively intervene. The present investigators are engaged in the iterative development of HALO (Health And Lifestyle Behaviors In Offspring), a parent-led behavioral intervention targeting a high-risk pediatric population (i.e., residing offspring ages 6-12; body mass index [BMI] > the 70th and < 120% of the 95th percentiles of mothers with severe obesity) that is uniquely well- timed, when mothers are highly engaged in behavior change and losing weight during the first post-MBS year. The current application is the Phase 2 pilot and feasibility randomized clinical trial of HALO relative to enhanced standard of care with 50 mother/child dyads (randomized n = 25 per arm). In addition to examining HALO feasibility, acceptability, and maternal satisfaction, we will examine efficacy of HALO on the prevention of child excess weight gain. We will also assess change in secondary outcomes including factors thought to be mechanisms for change in child zBMI (e.g., child daily intake of total kcals), changes in the HFE (e.g., presence per person of total kcals), and parenting behaviors related to child feeding (e.g., restriction, monitoring). Demonstration of HALO’s feasibility and initial efficacy will serve as the groundwork for a Phase 3 R01 application to test for sustained healthier child weight outcomes in the context of maternal MBS. HALO has the potential to revolutionize care pathways by creating a synergy of partnerships between pediatric and adult care to address a chronic intergenerational disease.