The main focus of this book is to provide an overview of the principles of molecular diagnostics in context of cytopathology specimens together with a basic understanding and working knowledge of the available technology, platforms, and clinical applications. The initial sections of the book summarize the pre-analytic aspects of molecular testing, including cytology specimen preparation and handling, specimen selection and evaluation, and workflow algorithms as well as the analytic considerations for a variety of nucleic acid and protein-based testing. The remaining section focuses on disease specific molecular testing for various organ-based applications.