A group of Brownies in the United States Girl Scouts is called a troop.
The term reflects the broader American scouting tradition, where a troop is a basic organizational group. Girl Scout troops bring members together for meetings, activities, badge work, service projects, and outdoor experiences. Brownies are the Girl Scout level generally associated with second and third grade.
The terminology varies internationally. In many Girl Guiding organizations, a group of Brownies is called a unit, while smaller subdivisions may use terms such as sixes or patrols. That international variation explains why “unit” can seem plausible, but for the United States Girl Scouts, “troop” is the canonical answer.
Girl Scouting in the United States began in 1912, when Juliette Gordon Low organized the first Girl Guide troop meeting in Savannah, Georgia. Brownies were later established as the younger Girl Scout level, and the troop structure remained central to American terminology.