Quite often people in our GENCOM group will ask about how to search for their records if they or one of their ancestors was adopted. FamilySearch has a very helpful page on the FamilySearch Wiki. This page has resources that anyone can use that might help them crack the walls of secrecy involved in gaining access to adoption records. The wiki page is titled, United States Adoption Research and provides some basic guidelines on how to move forward in their search, along with many excellent links to webpages where additional help can be found.
Happy ancestor hunting.