This project has the goal of understanding computational aspects of the immune system. The project extends earlier work by emphasizing the highly distributed memory and control structures of the immune system and integrating several earlier models. The following approach is taken: (1) identify an immune-system mechanism that appears to be interesting computationally, (2) write a computer program that implements or models the mechanism, (3) study its properties through simulation and analysis, and (4) demonstrate its capabilities, either by applying the model to a biological question of interest or by showing how it can be used profitably in a computer science setting. Computer security in open environments (e.g., the Internet) is used as a motivating application and as an on-line environment in which to test the integrated adaptive computer immune system. Other applications include: biological modeling, vaccine design for mutating viruses, and anomaly detection in manufacturing. Distributed and secure computing will play a central role in almost any future networked computer system, and this project contributes a principled approach to this topic, particularly the problem of how to deploy active truly autonomous agents across large networks