Background: Approximately 8.8% of US high school students attended private schools in 2015. Few studies have characterized health risk behaviors among these students or compared prevalence of behaviors between students in private and public schools using a contemporary, nationally representative sample. Methods: Pooled 2007-2017 national Youth Risk Behavior Survey data were used to estimate the prevalence of 35 health risk behaviors for 89,848 public and private high school students. Unadjusted prevalence ratios were used to compare prevalence by school type. Differences in behaviors by school type were explored by sex and grade. Results: Among private school students, the prevalence ranged from 5.0% to 31.9% for sexual risk behaviors; from 0.8% to 30.1% for substance use behaviors; from 0.7% to 21.8% for behaviors related mental health and suicide; from 3.2% to 6.8% for violence victimization experiences; and from 3.1% to 52.9% for behaviors related to unhealthy diet and physical inactivity. Private school students were less likely than public school students to report most behaviors; differences by school type were generally consistent across sex and grade. Conclusions: Students in both public and private schools reported health risk behaviors. Findings might inform prevention activities by identifying behaviors to prioritize in each school setting.