Operation World is a reference book and prayer guide, begun by Patrick Johnstone and continued by Jason Mandryk, both from WEC International, a Christian mission agency.

Operation World has been translated into several other languages: Spanish, French, Dutch, German, Portuguese, Russian, Korean, Indonesian, and simplified Chinese.

In the missionary tradition of the Dorothea Mission and WEC International, the team behind the production of Operation World consists only of volunteers (i.e., no salaried staff).

Data is gathered from sources including primary input from national Christian church leaders, missionaries, and researchers.

The Operation World database includes information on approximately 33,000 Christian denominations, 16 major religions, 1,200 missions agencies, and 16,000 fields of ministry.