Background: Consumption of ultra-processed foods is increasing in the United States (U.S.), compromising diet quality and its associated risk with cardiometabolic diseases. The Socio-Ecological Model provides a framework for understanding factors that may be associated with dietary outcomes, and current evidence is mixed regarding the association between these factors and dietary outcomes. Due to our limited understanding about this relationship, particularly within the family context, this study examines the association between socio-environmental factors and dietary outcomes in U.S. parent-adolescent dyads.Purpose: This study examines interdependent associations between socio-environmental factors and consumption of nutrient-dense foods (NDF) and ultra-processed foods (UPF) in a demographically representative sample of U.S. parents and adolescents. Methods: Parent-adolescent dyads enrolled in the Family Life, Activity, Sun, Health, and Eating (FLASHE) study were each administered online surveys about their diet and potential related factors. Parent-adolescent dyads (n=1,850) completed questions used for analyses, while the sample size was reduced to a total of 1,581 dyads in the final models. Multilevel linear regressions were used to test study hypotheses. Results: Results from standardized multilevel linear regression tests revealed that different combinations of socio-environmental factors are associated with parent-adolescent NDF and UPF consumption. Among significant factors, NDF consumption correlated positively with the type of stores visited by the parent to purchase food (βp=0.66, p=0.000; βa=0.50, p=0.000), with a greater effect on parents (Δβ=0.16, p=0.041), NDF consumption also correlated negatively with eating behavior away from the home (βp=-0.17, p=0.036; βa=-0.59, p=0.000), with a greater effect on adolescents (Δβ=-0.42, p=0.000). Regarding UPF consumption, findings suggest a negative correlation with food availability in the home (βp=-0.67, p=0.000; βa=-0.90, p=0.000), with a greater effect on adolescents (Δβ=-0.23, p=0.005). The conditional effect of adolescents given average scores on continuous measures associated with UPF consumption (Δβ=1.00, p=0.000) was significant. Conclusions and Implications: Household-level factors were stronger predictors of dietary outcomes compared to other socio-environmental influences at neighborhood levels (i.e., school). In adjusted models, adolescents consumed more UPF than parents, suggesting the presence of additional adolescent-specific factors that need further research. Interventions in the home environment that aim to reduce UPF and improve NDF intake are warranted.