This article is adapted from an invited address sponsored by European Humanities University, Vilnius, Lithuania, on the occasion of the 200th anniversary of Soren Kierkegaard’s birth. In this article, I show how Kierkegaard’s philosophy—in particular that depicted in Fear and Trembling and the Sickness Unto Death—runs through each of my major books on existential psychology and practice, from The Paradoxical Self to my latest work The Polarized Mind. I conclude that Kierkegaard, like William James succeeding him, is one of those rare philosophers who is likely to have as much impact on philosophy and psychology’s future as he had on their past.