Background Previous studies have identified the role of family support in mitigating the stress of parents caring for a child with intellectual disability. Less is known about families whose members are willing but unable to support each other because of geographical, structural and economic barriers. Our study examined the contribution to family quality of life (FQL) of family support beliefs, actual assistance from family members, as well as the moderating effects of ethnicity and household income. Method We conducted telephone interviews with 84 Latino and 61 non‐Latino mothers. Results Mothers who received more emotional support from partners and other family members reported a higher FQL, controlling for family characteristics. Familism beliefs were also associated with FQL, particularly for Latino mothers. Income was not a significant moderator. Conclusions These findings suggest that some predictors of FQL are partially moderated by ethnicity, while others may be powerful across diverse communities.