Summarized are results of field studies of small, cushion-forming species of Grimmia in high altitude mountain areas of New York State, Vermont, New Hampshire, and Maine, and of associated research with herbarium specimens from these regions. We here report eight species. Grimmia anodon is added to the flora of the Northeast, and new records and clarifications are presented for G. donniana, G. incurva, G. longirostris, G. milleri, G. sessitana, and G. trichophylla. Collections of these species came from rock types of varying composition (calcareous to acidic), sometimes different vegetation, and varying altitudinal ranges. In spite of these advancements in knowledge, Grimmia of the northeastern United States remains incompletely understood, taxonomically and ecologically.