Due to the knowledge economy emergence, many terminologies were added to the management studies’ literature such as knowledge work, knowledge workers, knowledge organizations and knowledge management. Most of these terms are still debatable in the literature and practice. This review will be critically discussing knowledge work and workers. Although many statistics and definitions supported the existence of knowledge work and thus the classification of knowledge workers as a distinctive working class, these terms haven’t reached a consensus. Still a lot of scholars believe that knowledge workers are nothing but a reclassification of the existing working classes with no strong theoretical and empirical evidence to support such a claim. Knowledge work and workers is believed to be terms that indicate the changing working conditions that affect all working classes in different intensities. This can be represented by the occupational knowledge intensification caused by different factors such as the increase in utilizing technologies at the workplace and growing market demands for customization. The review concludes that knowledge work and workers are still weak concepts and if they are to survive their definition and differentiation should be narrowed and cleared. Alternatively, such terms could be excluded and substituted by categorizing different emerging working classes into new professions, following the professionalization process.