Prevention programs for dating partner aggression should be based on knowledge about when such aggression starts and how it changes. Given the very few studies regarding such trends, changes in physical, psychological, and sexual aggression against dating partners were examined in 14- to 20-year-old Spanish high school students (N = 2,016). Overall, psychological aggression increased linearly, whereas physical aggression had a negative quadratic association, peaking at 16 to 17 years for males and females. Sexual aggression was infrequent, but it spiked at age 16 for males. Although physical aggression diminished in late adolescence, injuries as a consequence of such aggression increased linearly for females, and they were also significantly higher for females (14.9%) than for males (3%) at ages 18 to 20 years. The findings support the hypothesis that dating physical aggression for males and females peaks during middle-to-late adolescence and shows a similar developmental pattern to other antisocial and criminal behaviors. Prevention of dating aggression, escalation of such aggression, and prevention of injury should consider developmental trends in dating aggression.