Dear Colleagues, Synthetic biology is a broad and emerging discipline that capitalizes on recent advances in molecular biology, genetics, protein and RNA engineering and omics technologies. These technologies have transformed our ability to reveal the biology of the cell and the molecular basis of disease. This Special Issue on "Synthetic RNA and DNA Programming" features original research articles and reviews, highlighting novel aspects of basic molecular biology and the molecular mechanisms of disease that were uncovered by the application and development of novel synthetic biology-driven approaches.