This series documents the expansion project, designed by Albert Mayer's firm, Mayer, Whittlesey & Glass Architects, in which over the course of several years in the 1950s two new structures were built next to and behind the original building. Both buildings were named for the principal donors to the capital campaign: 69-76 West Twelfth Street was designated the Jacob M. Kaplan Building and 63-69 West Eleventh Street the Albert A. List Building. The original building at 66 West Twelfth was now named for Alvin Johnson, the school's influential president emeritus. In addition to the drawings for the new structures, the plans show many rooms in the original building renovated and repurposed for additional instructional and administrative space.

Plans pertaining to floors designated Intermediate “A” and “B” refer to the two levels above the first floor of the Kaplan Building, which abutted the two-story high auditorium in the Johnson building. Because the Intermediate “B”' ceiling was higher than the Johnson building ceiling, each floor above "B" in the Kaplan Building rises slightly higher than its corresponding floor in Johnson. Intermediate "A" and "B" floors were later renamed the second and third floors, respectively, shifting all floor numbers above them up by two in both the Johnson and Kaplan Buildings.

Plans indicate the transformation of the library on the fourth floor of the Johnson Building into classrooms and offices (the library was relocated to the first and second floors of the List Building). Plans for the penthouse of the Johnson building show that the art studio space was converted to office space; the apartment on the sixth floor was also refigured as office space.

The series consists wholly of construction plans for the three building complex. All plans are blueprints or another form of reproduction--there are no design drawings and no original drawings. Except for floor plans, listed first in the Architectural drawings subseries, all work is alphabetical by subject.