The strength of Brimmer's community stems from the relationships between the individuals who make up the school. Lower School students develop close bonds with their teachers and with each other. Each week the Lower School gathers in the theatre for a Share Assembly. Share Assembly activities include guest performers, storytelling, and school performances.

The Buddy System, which pairs older students in the Lower School with younger students, fosters friendship and a sense of belonging. Buddies eagerly look forward to sitting together at Share Assemblies and enjoy being together for special events like the Apple Picking Trip in the early fall, the Annual Buddy Walk, and special Theatre Outings.

Lower School families and their children come together for a variety of community-building events throughout the school year. First semester functions include a Lower School Picnic in September, two special assemblies on Visitors' Day in November, Winter Concert, and Lower School Food Drive just before school break in December. Second semester highlights include the Family Skating Night, Winterfest, and All-School Arts Festival. In addition to the regular schedule of events, informal and impromptu gatherings take place after school and at other times. All Lower School parents are invited to visit their child's classroom. To truly appreciate Brimmer's strong sense of community, it is important to tour the campus and talk to current students, teachers, and parents. Brimmer's family-like atmosphere remains one of its most distinguishing characteristics.