This study used a longitudinal dataset and lagged dependent-variable panel regression models to examine whether political and economic characteristics directly predict under-5-year mortality rates (U5MR), and moderate the effects of health services and environment on U5MR. We used a sample of 46 less-developed countries from 1980 to 2009. Our results showed that the effects of political and economic characteristics on U5MR varied by non-sub-Saharan and sub-Saharan countries. After controlling for baseline U5MR and other socioeconomic variables, while foreign investment and health services were negatively associated U5MR, democracy was positively associated with U5MR in nonsub-Saharan countries. In contrast, debt was positively associated with and democracy and foreign investment were negatively associated with U5MR in sub-Saharan countries. The interaction analyses indicated that for sub-Saharan countries, the effects of health services on U5MR only existed for countries with low foreign investment.