In this book, a programming model is developed that addresses the fundamental issues of "large-scale programming," unifying several concepts from database theory, object-oriented programming and designs of reactive systems. The model and the associated theory have been christened "Seuss. " The major goal of Seuss is to simplify multiprogramming. To this end, we separate the concern of concurrent implementation from the core program design problem. A program execution is understood as a single thread of control - sequential executions of actions that are chosen according to some scheduling policy - yet program implementation permits concurrent executions of multiple threads. As a consequence, it is possible to reason about the properties of a program from its single execution thread, whereas an implementation may exploit the inherent concurrency for efficient execution.