At its deepest level, life relies on information-based chemistry: DNA encodes programs for orchestrating chemical processes to accomplish tasks essential to living organisms, such as constructing molecular structures and making decisions based on molecular sensors. To better understand life, and more practically to develop programmable molecular technologies, a rich theory and practice for information-based chemistry is needed. Building on DNA nanotechnology and cell-free synthetic biology, we have been exploring how designable molecular mechanisms such as folding, self-assembly, catalysis, and motors can serve as the basis for molecular "programming languages". To do so requires integrating nucleic acid biophysics, computational simulations, abstract models of molecular computation, computational complexity theory, the development of compilers that transform high-level specifications into synthesizable nucleic acid sequences, and laboratory demonstrations of DNA systems performing sophisticated tasks at the molecular level. While falling far short of the sophistication of life and still unproven for technological applications, these investigations are helping to develop a new way of thinking about information-based chemical systems.