Boyd's Windmill, also known as Boyd's Wind Grist Mill, is a historic smock mill at Paradise Valley Park on Prospect Avenue in Middletown, Rhode Island.

John Peterson built the windmill at the corner of Mill Lane and West Main Rd.

The mill is a timber-frame structure, octagonal in shape, and about 30 feet (9.1 m) tall, with a rotating cap powered by eight vanes with canvas sheets.

In 1916 Benjamin Boyd removed the original vanes and powered the mill using a gasoline engine.

The windmill is open to the public on Sunday afternoons in July, August and September.