Suicide mortality varies widely across age, sex, race, and geography, far more than does mortality from the leading causes of natural death. Unlike the tight correlation between cancer mortality and the incidence of cancer, suicide mortality is only modestly correlated with the incidence of suicidal acts and other established risk factors for suicidal behavior, such as major psychiatric disorders. An implication of this modest correlation is that the proportion of all suicidal acts that prove fatal (the case fatality ratio) must account for a substantial portion of the (nonrandom) variation observed in suicide mortality. In the United States, the case fatality ratio is strongly related to the availability of household firearms. Findings from ecologic and individual-level studies conducted over the past two decades illustrate the importance of accounting for the availability of highly lethal suicide methods in efforts to understand (and ultimately reduce) disparities in suicide mortality across populations.