Various 
Psychology Library Editions: History of Psychology [PDF ebook] 
8 Volume Set

Originally published between 1928 and 1987, the volumes in this set provide an interesting look back at how psychology has developed as a discipline and some of the problems it has encountered along the way. It includes volumes focusing on the history of specific fields such as developmental and experimental psychology, as well as examining the roots of psychological theory as a whole and how it has informed many of the fields of psychology we know today.