Anchieta was pioneer in transcribing the Old Tupi language and authored the first published work on that language, a "pathbreaking" grammar, "Arte de gramática da língua mais usada na costa do Brasil", written in 1555 and published in 1589. According to one assessment, "His grammar and dictionary still rank among the best ever produced of a Brazilian language, nearly 500 years later... Anchieta was a dedicated linguist whose work can be considered the beginning of Amazonian linguistics (indeed it would not be stretching matters too far to call his work the beginning of linguistics in the Americas." His written works in the indigenous language span theology, religious instruction, theater and poetry.