Grundy's is a wizarding department store in the Goblin Market in Chicago, Illinois.

The first floor of the store consists of an Ocular Department, a Household Charmed Goods Department, Furniture, Home Decorations and Remodeling, Wizard Appliances, Clockworks, Bath & Body Charms, and a Brooms and Carpets section. On upper floors are Glass and Potionwares, Cauldrons, Toys and Children's Charms, Sporting Goods, Wizard School Supplies, Wands & Wandcare, a Familiars and Pets Department, Muggle Imports, and more. In the Clockworks section, Alexandra Quick sees a Tockmagi Household Clockwork Golem for the first time.

Angelique Devereaux, Anna Chu, Constance and Forbearance Pritchard, David Washington, Darla Dearborn and Quick visited Grundy's toward the end of the summer of 2007 to shop for school supplies prior to their sixth-grade year at the Charmbridge Academy. Washington and Quick got into a fight with Benjamin and Mordecai Rash and Larry Albo in the cafeteria when Albo and the Rash brothers insulted them.

The five got Barred from the store for the fight, which Quick discovered in August 2008, when she attempted to return to the store. When she tried to walk through the door, she was stopped as if she'd walked into a wall; she learned that only a manager could lift the Bar, as he had already for Albo and the Rash brothers. Later, in the cafeteria, the Charmbridge students met a half-dozen students from the Blacksburg Magery Institute on exchange, and saw Dearborn publicly humiliated by Martin Nguyen.