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. It should also be noted that much of his English language work is actually directly related to, or translated from, Gaelic equivalents.

Crichton Smith's work also reflects his dislike of dogma and authority, 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. Despite his upbringing, Crichton-Smith was an atheist. 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.

Elderly women and alienated individuals are common themes in his work.

Crichton Smith's poetry quite often had a character perhaps based on his mother. He also typically used natural images to convey emotion.

His poetry includes:

• Culloden and After (1961) - an attack on that period in British history, especially "Bonnie Charlie".
• Old Woman (1965)
• The Iolaire (date)