In the early to mid-20th century, Modernism grew out of the needs of a changing world. Population growth and new technologies, like mass transit and mass production, required new structures, including stations and factories.

In architecture, Modernism is characterized by the use of industrial methods and materials and by a sculptural approach to space. It is from Modernism that we have the now ubiquitous design dictum that “form follows function.” The buildings evoked the spirit of Modernist “progress” and the hope and wonders of technology. Typically, a Modernist building has repeated geometric forms, large unbroken planes, a certain lack of ornamentation, visible use of industrial materials that informs the design, and the agreement of the exterior structure with the interior space.

In Europe, architects in many different countries were developing their own forms of Modernism. This loose collective became an architectural movement known as the International Style, led perhaps most famously by Le Corbusier and Walter Gropius. American Modernism's great architects include Louis Kahn, Ludwig Mies van der Rohe, and Frank Lloyd Wright.

Long-time member Morris Jellison worked for Paul Hayden Kirk several years after University Unitarian was built. He notes that preliminary sketches showed a round sanctuary, far different from the final rectangular form.

Modernism was supposed to solve problems with engineering. Unfortunately, Modernist buildings are very susceptible to leaks, provide poor spaces for working or expansion, and report other faulty systems. Still, with an emphasis on minimal ornamentation, Modernist buildings are beautiful in their structure and space.