The advent of combinatorial approaches to problems at the interface between chemistry and biology has had a profound impact on areas ranging from drug discovery to protein chemistry. One area of intense work has been the application of combinatorial libraries of proteins to the discovery of proteins with novel functions or properties (1 ). Numerous methods exist for creating these libraries, examples being DNA shuffling and incremental truncation (2 ,3 ). However, library creation is only one phase of a combinatorial solution to protein discovery. The second equally important phase is the screening of the library for proteins displaying the desired property or function. This chapter focuses on a method for examining libraries for enzymatic function.