New fieldwork has brought the entire 'orthopteroid' fauna of the Galapagos Islands to a total of 57 species, in 37 genera, and 7 insect orders. Identification keys and distributional details are given for the 24 species in the order Orthoptera (s.str.) (Ensifera and Caelifera). Of these, 19 species (and 2 genera) are endemic, 2 species are native (naturally occurring elsewhere in tropical America), and 3 species are presumed to have been introduced by humans. It is assumed that ancestral natural colonizations occurred through the air by flying ancestors or through rafting and ocean-surface transport by flightless ancestors (in Gryllidae; Nemobiinae and Mogoplistinae). Of the indigenous (non-introduced) species, 71% of Orthoptera (s.str.) and 72% of all orthopteroids of the Galapagos Islands are now flightless in one or both sexes. Considering the richness of the total orthopteroid fauna in mainland Ecuador, the island fauna is very highly impoverished. Evolution and diversification are modest in the Galapagos orthopteroids compared with some other plants and animals. Some species (probably descendant from coastal arid zone ancestors) are now limited to either moist highland or cave habitats. Species richness is significantly positively correlated with island ecological complexity and island area.