The sample for the study consisted of all babies born between April 1, 1972, and March 31, 1973 in Dunedin, a New Zealand city with a population of 120,000. The participating sample included 1,037 babies and was followed for more than 20 years. Of the total sample, 625 were dating, 223 were cohabitating, 27 were married, and 80 had no relationship in the previous year. Researchers found three times more women (18.6 percent) than men (5.7 percent) said they kicked, bit, hit with a fist, or hit with an object. When less severe forms of violence were examined, such as throwing something, pushing, grabbing, shoving, and slapping, the rates were 37 percent for women and 22 percent for men. Men and women involved in severe partner violence had fewer years of education. Male perpetrators had been unemployed an average of at least 20 months, compared to 6 months for the other males. Males who were violent also reported more symptoms of alcohol dependence and drug abuse; 72 percent said they used two or more different drugs in the previous year, compared to 15 percent of the entire male sample. About 50 percent of male perpetrators of partner violence had also assaulted others in the past year, compared to 20 percent of the entire male sample. Crime problems in New Zealand and the United States are briefly compared, and possible explanations for the study findings are offered.