--- - |2 Abstract Human cooperative behavior has long been thought to decline under adversity. However, studies have primarily examined perceived patterns of cooperation, with little eye to actual cooperative behavior embedded within social interaction. Game‐theoretical paradigms can help close this gap by unpacking subtle differences in how cooperation unfolds during initial encounters. This study is the first to use a child‐appropriate, virtual, public goods game to study actual cooperative behavior in 329 participants aged 9 to 16 years with histories of maltreatment (n=99) and no maltreatment (n=230) while controlling for psychiatric symptoms. Unlike work on perceived patterns of cooperation, we found that maltreated participants actually contribute more resources to a public good during peer‐interaction than their non‐maltreated counterparts. This effect was robust to controlling for psychiatric symptoms and peer problems as well as demographic variables. We conclude that maltreatment may engender a hyper‐cooperative strategy to minimize the odds of hostility and preserve positive interaction during initial encounters. This, however, comes at the cost of potential exploitation by others. This article is protected by copyright. All rights reserved. - Developmental Science, Volume 0, Issue ja, -Not available-.