Kees L. M. Cornelissen, SocD is a certified psychotherapist with a private practice and co-founder of an open psychotherapeutic facility in the Netherlands. For many years he co-lead the Dutch ISTDP association (VKDP) as a board member, and together with Josette ten Have-de Labije he is still involved in running training programs in the Netherlands and in other European countries. He holds a degree in sociology from the University of Amsterdam.
During his career, he has completed training in group analysis, client-centered therapy, and transactional analysis, and has become a teacher and supervisor in several psychotherapeutic modalities. In 2005, he developed and founded the only existing inpatient group therapy program based on ISTDP, followed by several day treatment programs. He gained knowledge, theory and practice of ISTDP under H. Davanloo in Canada and then trained in ISTDP in the Netherlands with Josette ten Have-de Labije.
He is currently an IEDTA-certified ISTDP teacher and supervisor and a member of the editorial board of the Ad Hoc newsletter, as well as co-leading several international ISTDP basic training groups in Norway, England, Poland and the Netherlands. He speaks at national and international conferences, has written several articles on specific topics in the application of the ISTDP technique and a book on R-ISTDP (2007).
He works at Viersprong, a national personality disorders treatment center and is head of the department of psychodynamic psychotherapy, including ISTDP in South Holland, currently developing a knowledge center in the area of ISTDP in the Netherlands. He has also published several scientific articles on the impact and follow-up of ISTDP treatment.