This paper explores the use of bundling to reduce adverse selection in insurance mar-kets and its application to social health insurance programs. When the choice to buy health insurance is made at the household level, bundling the insurance policies of household mem-bers eliminates the eﬀect of adverse selection within a household since the household can no longer select only sick members to enroll. However, this can exacerbate adverse selection across households, as healthier households might choose to drop out of the insurance market. The net eﬀect of this trade-oﬀ depends on the characteristics of the household demand for medical care and risk preferences. I explore this issue using individual survey data on insur-ance enrollment and medical spending in Vietnam that contain detailed information about the structure of the household. The reduced-form evidence suggests that income, own-price and cross-member substitution eﬀects play important roles in the demand for medical care, which aﬀects a household’s selection of members into insurance. I then develop and estimate a model of household insurance bundle choice and medical utilization that accounts for these features. The results suggest that much of the adverse selection is concentrated within the household. Counterfactual analysis reveals that under optimal pricing, household bundling yields signiﬁcantly higher consumer surplus and insurance enrollment than individual pur-chase. Furthermore, the insurance market is less susceptible to complete unraveling under household bundling.