This supplement contains documentation on all the derived variables contained in the PIRLS and prePIRLS 2011 data files that are based on background questionnaire variables. These variables were used to report background data in the PIRLS 2011 International Results in Reading report, and are made available as part of this database to be used in secondary analyses. This supplement has four sections corresponding to each background questionnaire from which reporting variables are derived: (1) Student Questionnaire; (2) Home Questionnaire (Learning to Read Survey); (3) Teacher Questionnaire; and (4) School Questionnaire. The following information is provided for each derived variable: (1) Derived Variable Name; (2) Variable Label; (3) Title of International Report Exhibit; (4) Report Location; (5) A procedural description of how the derived variable was computed, including missing data rules if different from the general missing data rule described herein; and (6) Information about whether the variable was available in the previous cycle. [For the "PIRLS 2011 User Guide for the International Database," see ED544357. For Supplement 1, see ED544359. For Supplement 2, see ED544360. For Supplement 4, see ED544358.]