Schleyer began studying law at the University of Heidelberg in 1933, where he joined the "Corps Suevia", a student fraternity. In 1939 he obtained a doctorate at the University of Innsbruck. Early in his life he became a follower of National Socialism. After a stint in the Hitler Youth, the youth organization of the National Socialist Party, he joined the SS on 1 July 1933, SS number Nr. 221.714, and was an SS Untersturmführer (Second Lieutenant). During his studies he was engaged in the Nazi student movement. One of his mentors at this time was the student leader Gustav Adolf Scheel.