The transition period of the productive cycle of dairy cows is the most critical and important phase of the entire cycle. Therefore, thorough knowledge of physiology and the challenges that the cows must face to achieve an optimal transition from pregnancy to lactation is fundamental for the productive and reproductive success of the dairy cow. Therefore, this book offers a comprehensive and detailed description of all the metabolic and physiological processes that the cow in transition experiences and how this period can be managed efficiently and rationally, fundamentally considering the nutritional and feeding management and the cow-comfort of the cow to achieve a smooth and efficient transition from pregnancy to lactation and a favorable immune status to avoid the appearance of periparturient diseases.