In their study Wilson and Daly concluded that for every 100 U.S. men who kill their wives, about 75 women kill their husbands; this spousal "sex ratio of killing" (SROK) is more than twice that in other Western nations. The current study examined the SROK for the United States by using data obtained from the Federal Bureau of Investigation's Supplementary Homicide Report to determine if Wilson and Daly's conclusion can be supported. Although the data analysis confirmed Wilson and Daly's summary findings, the results show that the SROK is an elastic measure, varying over time, race, and ethnicity. In many segments of the U.S. population, the SROK is comparable to the sex ratio of killing for other Western nations. Moreover, the differences between various racial groups in the United States are greater than the differences between the United States and Canada, Australia, and Great Britain, respectively. The authors of this study suggest that socioeconomic factors and family structure are the major reasons for the disparity in the SROK for different racial groups in the United States and abroad. The implications of these findings for future research are discussed. 3 tables, 1 figure, and 57 references