Leon Lojk (1937 – 2014), Slovenian psychologist and psychotherapist was one of Glasser’s closest colleagues and monitored the development of the author’s ideas and searched for the justification of those ideas in philosophy and the achievements of modern science. Senior instructor at William Glasser International, and a founder of the Training Centre for Choice Theory and Reality Therapy in Slovenia (in 1996) he established the evidence that Choice Theory Psychology as well as Reality Therapy has its foundations in science and philosophy. His “Scientific Argument for Reality Therapy” was the basis of Reality Therapy recognition in Europe as scientifically grounded psychotherapeutic approach.

In 1999 Leon established European Association for Reality Therapy (EART). Under his leadership EART gain full acceptance as a regular member of the European Association for Psychotherapy (EAP) by the EAP in Brussels, 2008 and Reality Therapy was recognition as relevant psychotherapy approach in Europe.
Moreover, in 2009 the Training Centre for Choice Theory and Reality Therapy was established as the European Institute for Reality Therapy (EIRT) which was in 2011 accredited by the EAP for providing Reality Therapy Psychotherapy training in Europe.

He was an author of numerous articles and co-author of several books. His book “Reality Therapy: Theory and Practice” he was  co-authored with his wife Boba Lojk was published post mortem in 2020.