User profile integration from multiple social networks is indispensable for gaining a comprehensive view on users. Although current social networks provide access to user profile data via dedicated apis, they fail to provide accurate schema information, which aggravates the integration of user profiles, and not least the adaptation of applications in the face of schema evolution. To alleviate these problems, this paper presents, firstly, a semi-automatic approach to extract schema information from instance data. Secondly, transformations of the derived schemas to different technical spaces are utilized, thereby allowing, amongst other benefits, the application of established integration tools and methods. Finally, as a case study, schemas are derived for Facebook, Google+, and LinkedIn. The resulting schemas are analyzed (i) for completeness and correctness according to the documentation, and (ii) for semantic overlaps and heterogeneities amongst each other, building the basis for future user profile integration. Copyright is held by the International World Wide Web Conference Committee (IW3C2).