Crichton Smith was brought up in a Scottish Gaelic speaking community, learning English as a second language once he attended school. Friend and poet Edwin Morgan notes that unlike his contemporaries (such as Sorley Maclean and Derick Thomson), Crichton Smith was more prolific in English than in Gaelic, perhaps viewing his writing in what, from Crichton Smith's view, was an imposed non-native language as a challenge to English and American poets. However, Crichton Smith also produced much Gaelic poetry and prose, and also translated some of the work of Sorley Maclean from Gaelic to English, as well as some of his own poems originally composed in Gaelic.

Crichton Smith's work also reflects his dislike of dogma and authority (he was an atheist), influenced by his upbringing in a close-knit, island presbyterian community, as well as his political and emotional thoughts and views of Scotland and the Scottish Highlands. A number of his poems explore the subject of the Highland Clearances, and his best known novel Consider the Lilies (1968) is an account of the eviction of an elderly woman during such times.