Research has shown that many behaviors previously thought to be purely psychological in origin do, in fact, have a physiological basis. To examine the relationship of smoking behavior to locus of control, and to attitudes toward, knowledge about, and behavior with respect to nutrition, 116 Canadian undergraduate students completed the Nutrition Questionnaire (consisting of attitude, knowledge, and behavior scales, and miscellaneous questions) and Rotter's Locus of Control Scale. Contrary to expectations, heavy smokers were found to be significantly more internal than either non-smokers or light smokers. No differences between smoking behavior and nutritional knowledge were found, but females were significantly more knowledgeable about nutrition than males. Females also responded more positively to the pro-nutrition factors of the Nutrition Attitude Scale. Caffeine and alcohol consumption were positively associated with smoking behavior and age. No sex differences in caffeine and alcohol consumption emerged. The findings suggest that with age such habits acquire increasing self-acceptance. (JAC)