The Global Estimates of Modern Slavery provides a picture of the scale and depth of modern slavery. The Global Estimates is the result of a collaborative effort between the International Labour Organization (ILO) and Walk Free, in partnership with the International Organization for Migration (IOM).

The global and regional estimates presented in this report are based on a jointly developed methodology summarised in the Annex and described in detail in the methodology report produced along with this 2021 Global Estimates report.

As was the case for the 2016 global estimates, the 2021 calculations are derived from multiple data sources, as no single source was sufficiently reliable. The principal sources are data from nationally representative household surveys – 68 forced labour surveys and 75 forced marriage surveys – jointly conducted by ILO and Walk Free, as well as the Counter Trafficking Data Collaborative (CTDC) anonymised case dataset on victims of trafficking collected by IOM and its partners in the process of providing protection and assistance services to trafficked persons.