Much attention has been given to the creation of adaptive user interfaces by the intelligence user interface design community. Such efforts have been driven by the recognition that different users are motivated by different needs and goals. Of late, driven by the same need for user customization, attention has focused on the research and development of adaptive agent technologies. However, in both of these areas--intelligent user interfaces and agents--little attention has been given to the cultural influences at play in the shaping of user needs and user modes of interaction and communication. This paper argues that culture underlies every aspect of social behavior and influences individual communication style, personality, character, motivation, knowledge, and cognitive mechanisms. The role of the individual within the group; modalities of communication, that is, the degree and mix of verbal and non-verbal communication; and group dynamics are all culturally dependent. Since this is the case, there is a need for socially intelligent agents that have mechanisms for understanding and producing communicative behaviors which are culturally reflective of the users and other agents with which they interact. If the cultural influences at work in shaping social behaviors are not factored into agent design, then communication between agents and users and amongst agents will be strained.