Project Summary/Abstract Childhood obesity is a serious public health concern that disproportionately affects low-income youth. Although family-based behavioral obesity treatment (FBT) is an efficacious intervention, low socioeconomic status is associated with poor treatment adherence and suboptimal response. Elucidation of modifiable risk factors that contribute to these treatment disparities in low-income families is crucial to maximize treatment response and prevent chronic weight-related comorbidities in high-risk youth. One important modifiable risk factor is non- adherence to dietary recommendations (i.e., dietary lapses), a strong predictor of obesity treatment non- response. According to goal-conflict theory of self-regulation, dietary lapses occur due to failure to inhibit responsiveness to momentary intrapersonal (e.g., negative emotions) and socioenvironmental (e.g., presence of unhealthy foods) cues that undermine core self-regulatory processes involved in eating-related self-regulation. Parents are key supporters of child eating self-regulation by modeling healthy eating habits and structuring the family food environment. As such, it is plausible that failed attempts by the parent to self-regulate their own eating behavior could trigger a dietary lapse in the parent and subsequently in the child, which may lead to weight gain over time. Importantly, low-income families may be at increased risk for dietary lapses due to the salience of intrapersonal and socioenvironmental cues in their natural environment that thwart attempts to self-regulate eating behavior. Data show that parent-reported momentary depressed mood and stress predict unhealthy parent feeding practices in low-income families. Further, socioenvironmental factors such as the presence and availability of unhealthy foods and prohibitive cost of healthy foods in low-resource neighborhoods may place additional demands on parents’ ability to select healthy foods on behalf of their child. To date, no studies have investigated whether or how these momentary cues lead to parent dietary lapses and subsequent child dietary lapses in low-income families, nor examined the impact of dietary lapses on parent and child weight change. Ecological momentary assessment, an assessment tool that collects repeated measures behavioral data in real time in the natural environment, is an ideal methodology to characterize dietary lapses given their sensitivity to contextual triggers. Further, EMA methods may offer incremental validity over traditional self-report methods that rely on biased retrospective recall of dietary adherence. Therefore, in a sample of 48 parent-child dyads (children aged 5-12) recruited from an ongoing FBT trial in low-income families, the proposed study will employ EMA to characterize the frequency, nature, and momentary context of parent dietary lapses, and examine their effects on subsequent child dietary lapses and parent-child weight change throughout 3-month FBT. Resu...