The Zoltan library is a collection of data management services for parallel, unstructured, adaptive, and dynamic applications. It simplifies the load-balancing, data movement, unstructured communication, and memory usage difficulties that arise in dynamic applications such as adaptive finite-element methods, particle methods, and crash simulations. Zoltan's data-structure neutral design also lets a wide range of applications use it without imposing restrictions on application data structures. Its object-based interface provides a simple and inexpensive way for application developers to use the library and researchers to make new capabilities available under a common interface.