Lilith is a general purpose tool to provide highly scalable, easy distribution of user code across a heterogeneous computing platform. Lilith's principle task is to span a heterogeneous tree of machines executing user-defined code in a scalable and secure fashion. Lilith will be used for controlling user processes as well as general system administrative tasks. Lilith is written in Java, taking advantage of Java's platform independence and intent to move code across networks. The design of Lilith provides hooks for experimenting with tree-spanning algorithms and security schemes. We present the Lilith Object model, security scheme, and implementation, and present timing results demonstrating Lilith' scalable behavior.