This article is a literature review of the psychological aspects of smoking behavior, highlighting personality characteristics of the smoker as an obstacle to smoking cessation. It describes the relation between smoking behavior and personality, and between smoking and the principal psychiatric disorders. Studies reveal that smokers tend to be more extroverted, anxious, tense, and impulsive, and show more traits of neuroticism and psychoticism than do ex-smokers or nonsmokers. The literature also reveals a strong association between smoking and mental disorders, such as schizophrenia and depression. Understanding the psychological factors associated with tobacco smoking and dependence can further the development and improvement of therapeutic strategies to be used in smoking-cessation programs, as well as of programs aimed at prevention and education.