Founded in 1914, the Department of Embryology of the Carnegie Institution of Washington has made an unparalleled contribution to the biological understanding of embryos and their development. Originally much of the research was carried out through experimental embryology, but by the second half of the twentieth century, tissue and cell cultures were providing histological information about development, and biochemistry and molecular genetics have taken center stage. This final volume in a series of five histories of the Carnegie Institution of Washington provides a history of embryology and reproductive biology spanning a hundred years. It provides important insights into the evolution of both scientific ideas and the public perception of embryo research, concluding with a reflection on current debates.