The Vocational Counseling Center was founded by decree of the Executive Board of the Office for Trade Improvement of the Chamber of Commerce, Industry and Trade in Zagreb on June 19 1931. The main task of the Center was to counsel young people in their choice of trade and crafts professions as well as professional schools, based on the medical examination of physical development and health and on the psychological assessment of their abilities and motivation. For seventeen years, more than 30,000 people, whereby more than 20,000 were psychologically tested, visited the Vocational Counseling Center (later renamed Vocational Counseling Department and Office for Work Psychology and Physiology). Although the number of examined and tested persons drastically increased in the last years of the Center/Department/Office activities, it had been closed in 1948 on ideological grounds. During the last three years of its existence and in the first years of new communist regime Office for Work Psychology and Physiology had increasing number of assessment of children with mental or physical disabilities especially those from some of Zagreb’s orphanages i.e. Children's house Marko Orešković. According to assessments, some of them were placed in Institute for the Education of Mentally Retarded Children in Velika Gorica. At the time of its closure, Office for Work Psychology and Physiology had employed a physician and five psychologists. One of them, Angelina Borić, authored the book „Mentalna nedovoljna razvijenost“ [Mentaly insufficient development] (1960) and was the co-founder of the College of Defectology in 1962. This paper analyzes the importance of the Office for Work Psychology and Physiology in grounding the work with children and youth with disabilities, especially in period after the WWII. Additionally, available archive data on applied psychological instruments and related diagnostic results were presented and discussed.