The impact of the universal coverage policy implementation in Thailand is demonstrated by the declining incidence of catastrophic health spending among Thai households-particularly among the poor. The households who remain at risk of catastrophe, as defined here, are better-off households, because of their preference for using private facilities. Others with increased likelihood of incurring catastrophic health expenditures are households with a greater proportion of elderly members, those having a member with a chronic illness or disability, and those having a member who experienced hospitalization. These determinants should prompt policy concerns to protect such households from financial catastrophe. [Health Affairs 28, no. 3 (2009) 1 The World Health Report 2000 noted that a high proportion of out-of-pocket payments for health care can keep a country from attaining equitable financing, because out-of-pocket payments for health care tend to be regressive and often impede access to health services. 2 Therefore, national health financing systems should be designed not only to facilitate access to health services when needed, but also to protect households from financial catastrophe through the development of risk pooling and prepayment mechanisms and reducing reliance on out-of-pocket payments.