Fifteen cases which met the criteria for 'dyadic deaths' were gleaned from police records in Philadelphia, Baltimore, and Washington, D.C. for the years 1974 and 1975, and combined for analysis with five additional cases from outside the primary study years for analysis. A comparison between the dyadic death sample and results of three other significant studies of homicide-suicide showed a high degree of similar characteristics. The typical American homicide-suicide offender was found to be a male in his mid-thirties to late thirties who killed his spouse or lover by a gunshot wound to the head. About half were Caucasian and 40 percent were found upon autopsy to have a positive blood alcohol level. Slightly more than half were employed, although only one worked at a white collar job or job of higher socioeconomic level. A known history of prior arrest was found in 50 percent of the cases; three-fifths of these included crimes against persons. In all cases, the offender knew his victim. The majority of cases occurred in the house, in the spring and fall months, and on a weekday. Suicide notes were left by 30 percent of the offenders. However, the dyadic event shares little similarity to the modal traits of the individual homicide or suicide. In general, the dyadic offender is more likely to be male and is more likely to kill/die in his home bedroom by means of a gun than is either the murderer or suicide. He is more likely to know his victim and less likely to have a history of prior arrest than is the typical homicide offender. Data from other studies produce varying interpretations regarding the perpetrator's motive. In the current sample, the dominant motive was a dependent-protective motive. The homicide victim is viewed as dependent upon the care of the perpetrator, who takes the victim's life and then his own when this protective role is threatened. Twelve references and four tables are provided.