The superfamily Chalcidoidea (Insecta, Hymenoptera) contains in excess of 26,000 described species worldwide, but with an estimated total diversity of more than 500,000 species the vast majority of species have yet to be discovered and described. Most chalcidoid species are parasitoids of hosts in at least 12 different insect orders, attacking the egg, larval or pupal stages, though phytophagy and other life cycles and hosts are known. Iran is the 18th largest country in the world and has a rich and diverse insect fauna, including Chalcidoidea. It is extremely interesting from a biogeographic point of view, and a paradise for an entomologist. This book summarizes the results of all prior research concerning species diversity of Iranian Chalcidoidea, including host records and distribution records by province in Iran as well as world distribution by country for 1,351 species of Chalcidoidea recorded from Iran through the end of 2019.