Peter Kalellis graduated from Princeton University with a Master of Education degree. For three years he attended the Blanton-Peale Institute of Religion and Health and a year later received his doctorate from Andover Newton Mass School of Psychology.
In 1975 he started a private practice in marriage and family therapy and individual psychotherapy in Westfield, N.J. He taught family interaction and counseling, and psychotherapeutic techniques at the Graduate School of Psychology at Seton Hall University for more than 12 years.
In the 1970s, Kalellis organized a team of American heart specialists to help patients in Athens, Greece. Thousands of heart disease victims received medical care as a result of the team's work. In 1991, Kalellis traveled to Kenya and Uganda with his wife Pat and daughter Katina and served as a missionary, teaching family living skills to the indigenous population.
For the last 35 years, Dr. Kalellis has been giving annual seminars for clergy on counseling for parishioners. He also conducts three day retreats for families and organizations all over the country.