The lichen family Teloschistaceae from the Galapagos is revised. Most of the species belong to the Caloplacoideae, two to Teloschistoideae and a few to Xanthorioideae, three subfamilies not validly published, which is remedied here. Four different datasets were analyzed using Bayesian inference. For the bulk of the species, a combined dataset of nrITS, nrLSU and mrSSU was analyzed. Additionally, three analyses were performed using nrITS to further investigate phylogenetic relationships within and between species in each subfamily, and in the genera Xanthomendoza and Squamulea. Four new genera are described: Lacrima, Oceanoplaca, Phaeoplaca, Sucioplaca. Twenty-four species are reported, of which ten are new to science: Caloplaca nigra, Lacrima galapagoensis, Oceanoplaca chemoisidiosa, O. sideritoides, Phaeoplaca tortuca, Squamulea chelonia, S. humboldtiana, S. osseophila, S. oceanica, and Xanthomendoza leoncita. Several new combinations are proposed and three species of Xanthomendoza are reduced to synonymy. Several new combinations and species placed into synonymy do not occur in the Galapagos, but are treated as a consequence of our taxonomic revision. Morphology, anatomy, secondary chemistry, distribution and molecular phylogenetic affiliation are presented for each species and a key is provided. Eight different chemical patterns are quantitatively described based on HPLC analyses. The new genus Lacrima includes L. galapagoensis, a species without vegetative propagules, and two densely isidiate species, L. epiphora and L. aphanotripta that are morphologically similar to 'Caloplaca' wrightii. The only species of Galapagos Teloschistaceae that contains xanthones is placed into Huneckia. Oceanoplaca includes two species with the new anthraquinone isidiosin, O. isidiosa and O. chemoisidiosa, while a third species, O. sideritoides, does not contain this secondary metabolite. Phaeoplaca camptidia has previously been reported from Galapagos, but our phylogenetic analysis suggests that it is a new species, here named P. tortuca. An isolated position is occupied by 'Caloplaca' diplacia, which we place in it its own monotypic genus Sucioplaca. Some Galapagos Teloschistaceae can be considered a 'residue' of unresolved Caloplaca s.l., i.e. the corticolous C. floridana is possibly related to the saxicolous C. nigra, while C. cupulifera can currently not be placed. Squamulea remains particularly problematic and includes S. phyllidizans, that is nested among otherwise unresolved Squamulea species. Based on molecular data, S. phyllidizans is close to 'Huriella'. 'Huriella' flakusii, described from Peru, is confirmed to occur in the Galapagos and the genus is reduced to synonymy with Squamulea. The Squamulea squamosa/subsoluta group remains largely unresolved, but the new species S. chelonia, S. humboldtiana, S. oceanica, and S. osseophila are phylogenetically distinct. Foliose Teloschistaceae are represented only by one species, described as Xanthomendoza leoncita, while the only fruticose species, Teloschistes chrysophthalmus and T. flavicans, are cosmopolitan.