Stewart's Department Store, also known as the Posner Building, is a historic department store building located on Howard Street at Baltimore, Maryland, United States. Catholic Relief Services is currently headquartered there.

The Stewart's Department Store structure was designed in 1899 by Charles E. Cassell and is a six-story brick and terra cotta steel-framed building detailed in a highly ornate Italian Renaissance Revival style. It features an exuberant ornamental detail includes fluted Ionic and Corinthian columns, lion heads, caryatids, wreaths, garlands, cartouches, and an elaborate bracketed cornice.

The Stewart's Department Store Building was listed on the National Register of Historic Places in 1999. The downtown flagship store was closed in 1978.

Stewart's began in 1901 when Louis Stewart acquired the building of Posner's Department Store on the northeast corner of Howard and Lexington Streets. The chain was a founding member of Associated Dry Goods or ADG. While many of Baltimore's downtown department stores during the 19th and early 20th centuries were founded by German-Jewish immigrants, Stewart's was a non-Jewish owned department store, although the original founders Samuel and Elias Posner were Jewish.

Stewart's opened its first suburban store in 1953. The 110,000-square-foot (10,000 m) store on York Road was located near the city/county line. Built on two levels and surrounded by parking, the store was designed to “blend into the suburban area around it.” The design included broad expanses of glass from floor to ceiling, “screened by Fiberglas curtains containing 600 square yards of materials.” Elaborate murals of Homewood House, the Washington Monument and the Federal Hill skyline decorated walls in the store, and a restaurant with a Chesapeake Bay theme became a destination for northern shoppers.

Four other stores followed in the 1960s and 1970s. They included Reisterstown Road Plaza in 1962, Timonium Mall in 1969, Westview Shopping Center (an addition to a 1958 Mall) in 1969, and the store's final branch at Golden Ring Mall in Rosedale, Maryland, in 1974.

Suburban stores were converted to ADG's Caldor discount chain in 1983.

• Baltimore's Bygone Department Stores: Many Happy Returns. The History Press. 2012. ISBN 978-1-60949-667-8.

• Stewart's Department Store, Baltimore City, including photo from 1998, at Maryland Historical Trust
• Stewart's – Explore Baltimore Heritage
• "Downtown Department Stores, and other Retail Goodies" Baltimore
• "Photo of Reisterstown Road store interior
• Photo of Resisterstown Road store exterior
• "Camellia Room" at Stewart & Co. Reisterstown Road
• "Chesapeake Room" restaurant at Stewart & Co. Reisterstown Road Plaza
• Article about department stores in Baltimore