The article provides a comprehensive overview of the steroid and thyroid hormone receptor superfamily, highlighting their roles in molecular control of gene expression and physiological processes. The historical perspective of these receptors is discussed, including early discoveries of their functions in development and physiology. The evolution of understanding their structure and function is detailed, emphasizing the identification of conserved domains and the discovery of new receptors through comparative anatomy. The article also explores the functional domains of these receptors, such as hormone binding, DNA binding, and transactivation, and the mechanisms by which they regulate gene expression. The potential for multiple receptors for the same hormone and the implications for tissue-specific regulation are discussed. The role of these receptors in ontogeny and physiology, particularly in morphogenesis and developmental control, is examined. Finally, the article concludes by emphasizing the universal nature of the molecular mechanisms underlying developmental and physiological homeostasis, suggesting that these receptors play a crucial role in both embryonic development and adult organ physiology.The article provides a comprehensive overview of the steroid and thyroid hormone receptor superfamily, highlighting their roles in molecular control of gene expression and physiological processes. The historical perspective of these receptors is discussed, including early discoveries of their functions in development and physiology. The evolution of understanding their structure and function is detailed, emphasizing the identification of conserved domains and the discovery of new receptors through comparative anatomy. The article also explores the functional domains of these receptors, such as hormone binding, DNA binding, and transactivation, and the mechanisms by which they regulate gene expression. The potential for multiple receptors for the same hormone and the implications for tissue-specific regulation are discussed. The role of these receptors in ontogeny and physiology, particularly in morphogenesis and developmental control, is examined. Finally, the article concludes by emphasizing the universal nature of the molecular mechanisms underlying developmental and physiological homeostasis, suggesting that these receptors play a crucial role in both embryonic development and adult organ physiology.