Designed by the firm of Nagle Hartray Architecture in collaboration with interior design firm Eva Maddox Branded Environments, the Main Library is the culmination of design goals to create an important civic building that adds to the strong architectural heritage of Oak Park, reflects the diversity of the community, and minimizes the impact on the natural environment through the use of sustainable building materials and systems. At 104,000 square feet, it is a three-story building with a partial fourth floor for building systems. Underneath the building is a parking garage containing 79 parking spaces, including four accessible spaces. In 2004, the then new building was awarded the Chicago Building Congress Merit Award for Best New Construction - Suburbs, stating the project displayed "distinctive design, outstanding construction and a positive impact on the surrounding community." 

Environmentally friendly features

As of May 2018, the green roof has diverted more than 2.5 million gallons of rainwater runoff from area sewer systems, thus preserving infrastructure since the building opened in 2003. Some 12,500 square feet of the third floor roof holds a thin layer of soil and was planted with many native Illinois plants, including phlox and sedum. The architects designed the extensive green roof system, and Oak Park landscape architect Carol JH Yetkin selected plants that require minimal upkeep. The green roof improves the energy performance of the building and contributes to better air quality in the neighborhood. More green building features include:

LED light bulbs: The parking garage is visibly brighter and uses less than half the energy it originally did when the building opened.

Recycled rubber flooring: Most of the building is laid with recycled rubber flooring, with the majority of the rubber recycled from rubber tires. The surface is both durable and easy to maintain, and staff note that the flooring muffles sound, is comfortable to stand on, and easy to push loaded book carts over.

Organic complement: The architects designed the east facade to be covered in copper shingles manufactured from 75 percent recycled copper. The copper shingles are developing a patina over time and present an organic complement to adjacent Scoville Park. 

Unobtrusive shading: Ceramic fritted glass in the large windows overlooking Scoville Park provide unobtrusive shading that reduces heat gain.