Sudden Infant Death Syndrome (SIDS) is a leading cause of mortality among infants and is responsible for thousands of infant deaths every year. Prenatal smoking and postnatal environmental smoke have been identified as strong risk factors for SIDS. Given the link between smoking and SIDS, this paper examines the direct effects of cigarette prices, taxes and clean indoor air laws in explaining changes in the incidence of SIDS over time in the United States. State-level counts of SIDS cases are generated from death certificates for 1973-2003. After controlling for some observed and unobserved confounding factors, the results show that higher cigarette prices and taxes are associated with reductions in SIDS cases. Stronger restrictions on smoking in workplaces, restaurants and child care centers are also effective in reducing SIDS deaths.