Much research has investigated patterns and predictors of intimate partner homicide (IPH) which is defined as a homicide by a current or former legal spouse. Research conducted in both the United States and Canada found extreme partner age discrepancy was a risk factor for IPH in opposite-sex couples. The study examined three hypotheses: (1) the population-based risk of IPH is higher for all heterosexual intimate partner couples when their age discrepancy is large compared to age-similar couples; (2) the population-based risk of IPH with a man or women offender is higher for age-discrepant than for age-similar heterosexual couples; and (3) the association between the couple’s age discrepancy and risk of IPH is reduced or eliminated after controlling for the homicide offender’s previous arrest record. The study analyzed 2,577 homicides from the Chicago Homicide Dataset which included all homicides that occurred in Chicago from 1965 to 1996, in which the victim was killed by a current or former legal spouse, common-law spouse, or heterosexual boyfriend or girlfriend, and all victims and offenders were at least 18 years of age. Data supported the hypothesis that the risk of IPH is elevated for couples with a large discrepancy between their ages. Separate analyses for IPH committed by men and by women supported the hypothesis that the pattern is robust for both types of homicide. However, controlling for the homicide offender’s prior arrest record did not reduce or eliminate the association between the couple’s age discrepancy and risk of IPH. This did not support the hypothesis that the offender’s previous arrest record would explain the association between age discrepancy and homicide risk. Figures and references