Before European contact, natural grasslands covered relatively little of Hawai‘i, with a grass flora composed of ∼48 species including 40 endemics. Following the proliferation of cattle ranches after the Great Mahele (land division) in the 1840s, it was quickly realized that the native grasses were not suitable for high intensity grazing. This sparked the importation of “improved” pasture grasses and set the path toward the contemporary dominance of foreign grasses across Hawai‘i. The importation of foreign grasses for forage accelerated dramatically in the early 1900s with the establishment of the Hawai‘i Agriculture Experiment Station (HAES) on O‘ahu by the United States government. The HAES imported seed, trialed grasses in introduction gardens, and distributed seed to ranchers across the islands. I performed a systematic review of literature produced by the HAES and similar organizations, newspapers, herbarium specimens, and floristic treatments to compile a record for the timeline of grass introductions, provide detailed historical context surrounding the introduction of these grasses, and reassess the status of species of controversial nativity. In total, 577 grasses were introduced post-1778, 158 of which were likely accidental introductions whereas 419 were deliberately imported. There are 232 species of grasses naturalized in Hawai‘i, including 102 deliberately introduced and 130 likely accidental. Deliberate introductions comprise the majority of invasive species which invade natural areas, whereas most accidental introductions are weeds associated with human disturbances. While deliberate introductions largely plateaued after 1970, new accidental introductions and some deliberate introductions with long lag periods continue to naturalize, with 30 newly naturalized grass species recorded between 2000 and 2023.