Symptoms of psychological distress afect millions of canadians. Use of ani-anxiety & anidepressant medicaions has increased in last decade. Medical model: proposes that it is useful to think of abnormal behavior as a disease. Basis for many terms used to refer to abnormal behaviour: mental illness, psychological disorder, psychopathology (pathology- refers to manifestaion of disease) Became dominant way of thinking during the 18th and 19th century. Represented progress over earlier models of abnormal behaviour: before 18th century, abnormal behavior based on supersiions. Thought to be possessed by demons; vicims of god"s punishment. Disorders treated with chants, rituals, exorcisms; some were candidates for chains, dungeons, torture and death. Brought improvements in treatment of those who exhibited abnormal behaviour: illness vicims viewed with more sympathy. Medical diagnoses of abnormal behaviour pin potenially derogatory labels on people: being labelled carries social sigma. Many psychological disorders atributable to geneic/biological factors: appear to be more similar to physical illnesses.