This exploratory study was designed to examine the beliefs of youth users of alcohol and marijuana about the connections between their substance use and dating violence perpetration. Eighteen youth (ages 14-20 years old), who were primarily of Black or Hispanic race/ethnicity, participated in in-depth interviews about times when they had perpetrated dating violence. They were asked to reflect on whether and how they felt that alcohol and/or marijuana may have contributed. Responses coalesced around four major themes, which were that users believed that (a) Alcohol escalates minor conflict; (b) Alcohol exacerbates feelings of irritation and anger; (c) Marijuana reduces feelings of irritation and anger; and (d) Substances are used to cope with conflict-related stress. We conclude that momentary event-level research that investigates the immediate influence of alcohol and marijuana use on dating violence perpetration is needed and that dating violence prevention interventions should consider addressing substance use and substance-aggression expectancies.