This chapter describes the origin of the word “doula,” starting from its meaning in Greek up to its current uses and explores the international development of doulas in the U.S.A. and Europe. About the European realm, the reconstruction of the doulas’ development is based on the memories of the protagonists of the European experience, due to the lack of publications on this subject. The last section of this chapter describes research on the effectiveness of doula care, including medical, public health, and social science studies. Medical and public health researchers agree on the benefits of continuous support during labor and childbirth to reduce the duration, the use of drugs and analgesia, and the rates of caesarean and operative births, whereas social science research has focused mainly on the practices and strategies that doulas adopt. Finally, recent developments affecting the doula profession are explored.