Genetic counseling as a formal clinical service was defined in 1947, though the first study of its effectiveness was not published until 1966. This history can be broadly divided in to 3 periods: 1) 1947-1980, when the focus was primarily on prevention of disability, 2) 1981-1995, when the rationales for counseling began to shift and the first studies on the psychosocial effects of genetic counseling started to appear, albeit still largely focused on reproduction, and 3) 1996 - Present, when genetic counselors increased their presence in oncology, cardiology, and other non-reproductive areas of genetic counseling. Changes in outcome measures of genetic counseling have been intertwined with technological advances in genetic testing, better and more sophisticated outcome measures, the growing professional independence and clinical positions of genetic counselors, and the influence of social scientists particularly from behavioral psychology. Despite advances, assessment of the effectiveness of genetic counseling continues is complicated by a lack of widespread agreement about the most appropriate outcome measures as well as research design problems. Broadly speaking though, genetic counseling tends to improve information recall, improve psychological well-being, and is generally well-regarded by patients.