The biological model calls into question the genetic factor. The schizophrenia has demonstrated higher than average for first-degree relatives of a person who is affected. The social model implicates environmental factors, taking into account all the ways of life of the person, inserted into the network of relations and in its specific context. Social factors such as discrimination, low educational level, family violence, may contribute to an increased risk of developing schizophrenia. Another cause is the abuse of psychotropic substances, under which assumes a particular importance of tobacco smoking and nicotine addiction. The knowledge of the causes that determine the onset or favor the evolution of a disease as devastating as schizophrenia, can be quite helpful to reformulate their lifestyle and relationship dynamics.