Development depends on tightly regulated genetic programs, intercellular signaling, and epigenetic modulation — this volume digs into those mechanisms. It presents transcriptional networks, signaling pathways (e.g., Wnt, Hedgehog, Notch), and regulatory RNAs that orchestrate cell fate decisions and tissue patterning. Comparative chapters draw lessons from model organisms and translate discoveries to human developmental disorders and diagnostics. Sections on experimental methods, gene editing, and prenatal screening provide practical context for modern developmental genetics. Ethical, translational, and therapeutic considerations are discussed to ground readers in real-world implications. The result is a rigorous yet accessible guide for graduate students and clinical geneticists.