Over the last few decades, impressive progress has been made in uncovering how embryonic development is driven by genes connected in complex regulatory networks. Our research goal is to endow these networks with quantitative and molecular information that makes it possible to precisely predict how the gene expression patterns that dictate cellular identity are prescribed by input activators and repressors, and the arrangement of binding sites for these transcription factors on the DNA. We test our models by systematically varying DNA regulatory architecture and by inventing new technology to perform precision measurements of the flow of information along the central dogma.