The homicide rate, which was low at the turn of the century, began to increase and reached a high during the 1920's and 1930's. The rate then declined until the early 1960's, when it began to rise sharply. A second peak was reached in 1974, after which the homicide rate began to drop again. During the twentieth century, homicide has involved males killing males in about 60 percent of the cases. In cross-sex killings, men have been more likely to kill women than vice versa. Homicide has consistently been primarily intraracial; however, the incidence of interracial murder has increased since the mid-1960's. During periods when homicide rates have generally been low, family and acquaintance killings have been most common. During high homicide periods, murder by strangers and murder for economic reasons have predominated. The use of guns in homicides fluctuates with the homicide rate. In periods of high homicide rates, the use of guns is also high. During lower homicide periods, the use of firearms declines. More attention should be paid to the relationship between markets for illegal goods such as liquor or drugs and the homicide rate. Different strategies should be used to reduce homicide during high activity periods than during low ones. During high activity periods, emphasis should be placed on investigation and identification of suspects; during low periods, on family education and increased family court resources. Notes which include references are included.