The article discusses institutional theories in economics and sociology. The discussion adopts W. Richard Scott's classification into regulative, normative, and discursive theories. A fourth alternative, habitual institutionalism, is also presented because of the problems encountered with the other theories. Pragmatically inclined habitual institutionalism presents a consistent theory of action wherein conscious action is derived from habitual action, which is also the basis of institutionalization. In addition, habitual institutionalism portrays human rationality more extensively than economists and sociologists have traditionally done. For these reasons, the difficulties associated with other institutional theories can be avoided.