Abstract: A system and method for aggregating user response data in a communication system such as an instant messaging (IM system). Aggregation is performed according to a hierarchical group addressing structure into which users are arranged. Data may be input, output and distributed in a structured data format. Aggregating information comprises collating, in each group in the hierarchical group addressing structure, information contained in responses from individual users in that group. Aggregating said information may further comprise collating, for each group in the hierarchical group addressing structure, information contained in responses from all child groups subordinate to that group. Because the grouping structure for addressing or routing is pre-existing, no additional grouping or categorising of individuals or responses is required.