The paper surveys selected alternative conceptions of rationality in contemporary and (especially) traditional economics and sociology. While the status of rationality as one of the master concepts, subjects and objectives of social science and philosophy has been further promoted in contemporary economics and sociology, questions often arise among economists and sociologists themselves as to its meaning or definition. As an attempt to help address this issue, the paper selects and examines a (limited) number of pertinent definitions and conceptions of rationality (...) from both economic and sociological theory. By virtue of its coverage of economics and sociology, this study is thoroughly interdisciplinary and contributes toward filling in a void in the current literature in which such studies are relatively rare. (shrink)