This supplement describes national adaptations made to the international version of the TIMSS 2011 background questionnaires. This information provides users with a guide to evaluate the availability of internationally comparable data for use in secondary analyses involving the TIMSS 2011 background variables. Background questionnaire adaptations include questions that countries were required to adapt, questions that were not administered, and questions that countries modified to suit their national context. National adaptations are presented in seven sections corresponding to the TIMSS 2011 background questionnaire types: (1) Fourth Grade Student Questionnaire; (2) Fourth Grade Teacher Questionnaire; (3) Fourth Grade School Questionnaire; (4) Eighth Grade Student Questionnaire; (5) Eighth Grade Mathematics Teacher Questionnaire; (6) Eighth Grade Science Teacher Questionnaire; and (7) Eighth Grade School Questionnaire. For each background question that was adapted, a national entry is included if the version of the question administered in a country was different from the international version. For each question, the following information is provided: (1) Question number; (2) Question stem and response options; (3) Variable name(s); and (4) National adaptation, listed by country. [For the "TIMSS 2011 User Guide for the International Database," see ED544555. For Supplement 1, see ED544556. For Supplement 3, see ED544558. For Supplement 4, see ED544559.]