The concept of the 'new middle class' emerged in sociological discourse to distinguish a growing segment of society from the traditional, propertied middle class (e.g., independent farmers, small business owners, professionals like doctors and lawyers who owned their means of production). The new middle class primarily comprises white-collar workers, managers, professionals, technicians, and administrative staff who do not own the means of production but rather sell their labor power, often intellectual or administrative, in exchange for salaries.

Its rise is closely linked to the expansion of industrial capitalism and the subsequent growth of the service sector and large bureaucratic organizations in the late 19th and 20th centuries. As corporations grew, there was an increased demand for managers, supervisors, clerks, and technical experts to organize and administer production and services. Unlike the working class, who perform manual labor, the new middle class typically engages in non-manual, often supervisory or intellectual, labor. They generally enjoy higher incomes, better working conditions, and greater job security than the working class, leading to distinct lifestyles, consumption patterns, and cultural values.

Sociologists like C. Wright Mills analyzed this group, highlighting their often ambiguous class position – neither owners nor manual laborers. They often identify with the values of the capitalist class (e.g., individualism, meritocracy) but share some characteristics with the working class (e.g., dependence on wages, lack of ownership). The new middle class plays a crucial role in the reproduction of capitalist society, often acting as a buffer between the capitalist class and the working class, and contributing to social stability through their aspirations for upward mobility and adherence to professional norms. Their political attitudes can vary, but they often lean towards maintaining the existing social order, albeit with demands for social reforms.