Reasoning about false beliefs of others develops with age. We present here an ACT-R model in order to show the developmental transitions. These start from a child’s reasoning from his/her own point of view (zero-order) to taking into consideration another agent’s beliefs (first-order), and later to taking into consideration another agent’s beliefs about again other agents’ beliefs (second-order). The model is based on a combination of rule-based and simulation approaches. We modeled the gradual development of reasoning about false beliefs of others by using activation of declarative knowledge instead of utility learning. Initially, in addition to the story facts, there is only one strategy chunk, namely a zero-order reasoning chunk, in declarative memory. The model retrieves this chunk each time it has to solve a problem. Based on the feedback, the model will strengthen a successful strategy chunk, or it will add or strengthen an alternative strategy if the current one failed.