The Petaluma Silk Mill is an industrial complex adjacent to the old waterfront area of Petaluma. The two-story brick building is rectangular under a low hipped roof of sheet metal with standing seams. A pair of three-story square brick tower stand forth from the long many-windowed facade.

The original building, designed by pioneer San Francisco architect Charles I. Havens in 1892, had a central tower and was half the length of the present structure. A silk vault, boiler plant, dyeroom, and other outbuildings not visible from the front, were also designed by Havens in 1892.

The enlargements, the first after the 1906 earthquake and the second in 1922, designed by noted Petaluma architect Brainerd Jones, were in compatible styling with the earlier portion of the mill. A slight difference in brick color identifies the stages of the building's construction: the central tower and two wings of the 1892 building, the addition to the north after 1906, and the tower and south wing added in 1922.

Sericulture, and more successfully, silk manufacturing were late 19th century manifestations of efforts in California to develop industry in the state. When San Francisco's Carlson-Currier Silk Manufacturing Company announced plans to relocate in the early 1890s, enterprising Petaluma businessmen launched a successful community campaign to entice the mill to their growth-minded river town.

Since then, the Old Silk Mill has symbolized industrial Petaluma, and its products have carried the town's name nationwide. First came silk thread and fine sewing products of Carlson-Currier and its successors. Since 1940, the Sunset Line & Twine Company has produced silk and synthetic fishing lines and more recently specialized natural and synthetic cords and tapes for industry and government.

Adapted from the NRHP nomination dated 4 February 1986.