Enzymes that use iron cofactors to activate molecular oxygen for hydroxylation, halogenation, desaturation, epoxidation, fragmentation, and peroxidation of unactivated carbon centers must guide their very reactive intermediates down preferred reaction paths to their specific outcomes. Our growing understanding of the general and enzyme-specific control strategies used by these enzymes has enabled the development of new catalytic capabilities and provided a roadmap for deployment of these enzymes in biocatalysis. I will provide recent examples of our elucidation of reaction pathways and control strategies, as well as the new reactions this insight has suggested.