We propose that people simplify their perceptions of their interactions by organizing them into discrete casual chunks. Once formed, these chunks presumably influence the extent to which people are aware of their influence on others, as well as their impressions of others. We anticipated that people would form self-causal chunks (e.g., my action causes my partner's action) when they possessed an offensive set and other-causal chunks when they possessed a defensive set. We also expected that a self-causal chunking strategy would make salient people's influence on their partners and thereby discourage them from concluding that their partner's behaviors reflected underlying dispositions. In contrast, we anticipated that an other-causal chunking strategy would obscure people's influence on their partners, thereby encouraging them to infer that their partners' behaviors reflected underlying dispositions. We tested these hypotheses by inducing participants to develop either a defensive or an offensive set prior to interacting with another person in a simulated arms race. After the interactions, we assessed the manner in which participants chunked their interactions, as well as their impressions of partners. The results supported our predictions. The implications of these findings for understanding conflict and misunderstanding in interpersonal relations are discussed.