The IEA's International Civic and Citizenship Education Study (ICCS) investigates the ways in which young people are prepared to undertake their roles as citizens in a range of countries in the second decade of the 21st century. ICCS 2016 is the second cycle of a study initiated in 2009. The ICCS 2016 user guide describes the content and format of the data in the ICCS 2016 international database. It introduces the use of weighting and variance estimation variables for analyzing the ICCS 2016 data, and provides a comprehensive overview of how to work with the IEA's International Database (IDB) Analyzer software. The ICCS 2016 user guide is accompanied by four appendices: the international versions of all questionnaires; an overview of national adaptations to the national versions of the ICCS 2016 international questionnaires; derived variables used in the ICCS 2016 international and regional reports; and a set of restricted-use civic knowledge items, together with their respective scoring guides, to illustrate the test contents. Over the past 50 years, the IEA has conducted comparative research studies in a range of domains focusing on educational policies, practices, and outcomes in many countries around the world. The association conducted its first survey of civic education in 1971. The reliable comparative data collected by ICCS 2016 will allow education systems to evaluate the strengths of educational policies, both internationally and within a regional context, and to measure their progress toward achieving critical components of the United Nations' 2030 agenda for sustainable development. [This guide was produced with Roma Tre Università degli studi. For the "ICCS 2016 Technical Report," see ED627443. For the "ICCS 2009 User Guide for the International Database," see ED544615.]