It has been known for decades that there is a link between alcohol consumption and domestic violence, but the research is slim when it comes to marijuana. The participants were male and female college students at least 18 years of age who had been in a relationship for at least a month, had face-to-face contact with their partner at least 2 times a week, and had consumed alcohol in the previous month. The studies asked participants to complete an online diary once a day for 90 days. Based on the results, the odds of physical, psychological, and sexual violence among men increased with the use of alcohol, and rose with each drink consumed, whereas marijuana use was unrelated to violence between couples. For women, alcohol use increased the odds of physical and psychological aggression, and marijuana use increased the likelihood of psychological aggression.