Information sampling about others’ trustworthiness prior to cooperation allows humans to minimize the risk of exploitation. Here, we examined whether preadolescence, a stage defined as in between childhood and adolescence, is a sensitive period for cognitive development underlying cooperation. We hypothesized that children in this age range would exhibit profound changes in adaptivity and sophistication of information sampling strategies and cooperation decisions. We further assessed how preadolescent children with Autism Spectrum Disorder (ASD, N=56) differed in both information sampling and cooperation decisions from their typically developing (TD, N=48) peers. TD and autistic 8- to 12-year-olds played an online information sampling trust game. TD and autistic children adapted their information sampling and cooperation to the various trustworthiness levels of the trustees. Groups differed in how age and social skills modulated task behavior. In the TD group, children with lower social skills adapted their cooperation decisions less to the trustee’s reciprocation probabilities, irrespective of age. Within the group of autistic children age was a more important predictor of task behavior. The older children were, the more they adapted to the trustee’s trustworthiness levels and the greater the influence of social skills on task performance. Computational modeling revealed that TD and ASD groups used a heuristic information sampling strategy – albeit older TD children were more efficient as reflected by decreasing decision noise with age. Prior to information sampling, autistic children expected trustees to be less trustworthy than TD children. This was reflected as lower prior beliefs in the ASD group compared with the TD group. Lower priors scaled with lower social skills across groups. Notably, groups did not differ in prior uncertainty, meaning that the priors of TD and autistic children were equally strong. Taken together, we found significant development in information sampling and cooperation in preadolescence and nuanced differences between TD and autistic children. Our study highlights the importance of deep phenotyping of children including clinical measures, behavioral experiments and computational modeling.