San Antonio Missions National Historical Park Boundary Expansion Act of 2010 - Directs the Secretary of the Interior to study lands within Bexar and Wilson Counties, Texas, to identify lands 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 lands 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 Park's boundary to include approximately 151 acres of additional land, as identified on the map entitled "San Antonio Missions National Historical Park Proposed Boundary Addition 2009," dated November 2009.
Prohibits the Secretary from using condemnation authority for the acquisition of lands or interests under this Act.