The study found that for this sample of 111 females and 37 males who assessed dating violence and 93 females and 41 males who assessed the sibling violence condition, male-initiated violence was less acceptable than female-initiated violence. Females were found to be less accepting of violence than males; and participants were more complacent toward sibling violence than dating violence in adolescence. Males reported perpetrating more injuries than females, and sibling violence was reported at higher frequencies than dating violence. All participants completed the Attitudes toward Interpersonal Violence Assessment (AIVA), a new, more ecologically valid measure for assessing attitudes toward violence in various interpersonal relationships, using behavioral responses to observed adolescent violence. Participants were asked to observe a videotape that depicts a male and female adolescent (both 15 years old) engaged in a violent interaction. The video was scripted so that the content would reflect a disagreement relevant to either dating partners or siblings. Four assessment scores were used to assess attitudes toward violence: the identification of violence, the intervention of violence, the total number of incidences of violence, and the participants reported level of being upset at what was being portrayed. 3 tables, 1 figure, 54 references, and appended coding sheet for the AIVA