Professor Ziegler has been Chair for Psychological Diagnostics at Humboldt on many occasions, and was made a full professor at the University in April 2012.
He is a prolific contributor to medical publications, as reviewer for the Australian Journal of Psychology, Diagnostica, International Journal of Obesity, International Journal of Psychology, Journal of Applied Social Psychology, Journal of Health Psychology, Journal of Individual Differences and the Journal of Personality among others.
He is the current editor-in-chief of the European Journal of Psychological Assessment.