Objective: To conduct the first population-based study comparing the frequency of child maltreatment among active-duty United States Air Force (USAF) maltreating parents before and after combat-related deployment. Method: By combining archival databases, we identified 2,287 children with a total of 2,563 substantiated maltreatment incidents perpetrated by USAF parents who deployed during an 85-month study period during Operation Iraqi Freedom/Operation Enduring Freedom. Results: Contrary to expectations, overall the frequency of child maltreatment was significantly lower after than before deployment, and this pattern did not vary as a function of the number of combat-related deployments. Further, the frequency of child maltreatment was lower postdeployment relative to predeployment for emotional abuse, mild neglect, and maltreatment not involving alcohol, but the frequency was higher postdeployment for child sexual abuse and severe child neglect, particularly when severe child neglect involved alcohol. Conclusions: In general, among children who experienced parental maltreatment by a deploying USAF parent, milder forms of child maltreatment were less common postdeployment, whereas severe types of child maltreatment were more common. Possible explanations implicate predeployment differences in resources and functioning or postdeployment differences in posttraumatic growth and maturation between parental perpetrators of mild versus more severe maltreatment. Postdeployment child maltreatment surveillance efforts should be vigilant for signs of severe forms of child maltreatment, which appear to be most likely to increase. (PsycINFO Database Record (c) 2014 APA, all rights reserved)