To amend Weir Farm National Historic Site Establishment Act of 1990 to authorize the limited acquisition of additional acreage for the historic site to permit the development of visitor and administrative facilities and to authorize the appropriation of additional amounts for the acquisition of real and personal property.

Amends the Weir Farm National Historic Site Establishment Act of 1990 to authorize the Secretary of the Interior to acquire not more than 15 additional acres of land contiguous or in close proximity to the Weir Farm National Historic Site, Connecticut, for the development of visitor and administrative facilities for the Site.

Limits: (1) any parking area for the visitor and administrative facilities to 30 spaces; and (2) items sold in the visitor facilities to educational and interpretive materials related to the purpose of the Site. Prohibits the sale of food.

Conditions development of visitor and administrative facilities on the acquired property to the Secretary entering into one or more agreements with the appropriate zoning authority of the towns of Ridgefield and Wilton for the purposes of: (1) developing the parking, visitor, and administrative facilities for the Site; and (2) managing bus traffic to the Site, including limiting parking for large tour buses to an offsite location.

Increases the authorization of appropriations for acquisition of real and personal property for the Site.