In addition to the following questions about PIRLS, more FAQs about international assessments are available at: http://nces.ed.gov/surveys/international/faqs.asp.
PIRLS focuses on three aspects of reading literacy:
The first two form the basis of the written test of reading comprehension. The student background questionnaire addresses the third aspect.
In PIRLS, purposes of reading refers to the two types of reading that account for most of the reading done by young students, both in and out of school: (1) reading for literary experience, and (2) reading to acquire and use information. In the assessment, narrative fiction is used to assess students' ability to read for literary experience, while a variety of informational texts are used to assess students' ability to acquire and use information while reading. The PIRLS assessment contains about an equal proportion devoted to each of these two purposes.
Processes of comprehension refer to ways in which readers construct meaning from the text. Readers focus on and retrieve information; make inferences; interpret and integrate ideas and information; and examine and evaluate content, language, and textual elements.
For more information on the purposes for reading and processes of comprehension, see the PIRLS 2011 Assessment Framework.