OBJECTIVE: The purpose of this study was to describe homicides of infants (children <2 years of age) in the U.S. METHODS: Cases were derived from the National Violent Injury Statistics System; 71 incidents involving 72 infant homicides were in the data set. Type 1 involved beating/shaking injuries inflicted by a caretaker; type 2 involved all other homicides (including neonaticide, intimate partner problem-related homicide, crime-related death, and other types). RESULTS: Seventy-five percent of the incidents were type 1 incidents, perpetrated mainly by men (83%; typically the infant's father or the boyfriend of the infant's mother). In 85% of the type 1 incidents, the infant was transported to the hospital, usually at the initiative of the perpetrator or another household member. In almost one half of the type 1 incidents, a false story was offered initially to explain the injuries. In contrast, the type 2 incidents (16 cases) were perpetrated mainly by women (11 of 16 cases) and involved methods such as poisoning, drowning, sharp instruments, or withdrawal of food and water; most infants were not taken to the hospital. Although 93% of incidents were perpetrated by caretakers, the large differences between the 2 incident types suggest different avenues for prevention. CONCLUSIONS: The circumstances involved in the type 1 homicides (beatings by caretakers) suggested that those attacks occurred impulsively, death was unintended, and emergency care was summoned, often with a false story. Previous abuse was suspected in more than one half of those incidents. DOI: 10.1542/peds.2008-3675