San Antonio Missions National Historical Park Boundary Expansion Act of 2012 - Directs the Secretary of the Interior to study land within Bexar and Wilson Counties in Texas, to identify land that would be suitable for inclusion in the San Antonio Missions National Historical Park. Requires the study to examine the natural, cultural, recreational, and scenic values and characteristics of the land within such counties.
Permits the assignment of Park employees to provide interpretive services, including visitor information and education, at facilities outside the Park boundary.
Modifies the boundary of the Park to include approximately 151 acres of additional identified land.
Permits the Secretary to acquire such land or any interest in such land by purchase from willing sellers, donation, or exchange.