Frost spent the years 1912 to 1915 in England, where among his acquaintances was the writer Edward Thomas. Thomas and Frost became close friends and took many walks together. After Frost returned to New Hampshire in 1915, he sent Thomas an advance copy of "The Road Not Taken". Thomas took the poem seriously and personally, and it may have been significant in Thomas' decision to enlist in World War I. Thomas was killed two years later in the Battle of Arras.
"The Road Not Taken" is a narrative poem. It reads naturally or conversationally, and begins as a kind of photographic depiction of a quiet moment in woods. It consists of four stanzas of 5 lines each. The first line rhymes with the third and fourth, and the second line rhymes with the fifth (a b a a b). The meter is basically iambic tetrameter, with each line having four two-syllable feet. Though in almost every line, in different positions, an iamb is replaced with an anapest. The variation of the rhythm gives naturalness, a feeling of thought occurring spontaneously, and it also affects the reader's sense of expectation. In the only line that contains strictly iambs, the more regular rhythm supports the idea of a turning towards an acceptance of a kind of reality: "Though as for that the passing there ... " In the final line, the way the rhyme and rhythm work together is significantly different, and catches the reader off guard.
It is one of Frost's most popular works. Some have said that it is one of his most misunderstood poems, claiming that it is not simply a poem that champions the idea of "following your own path", but that the poem, they suggest, expresses some irony regarding that idea.
Frost's biographer Lawrance Thompson suggests that the poem's narrator is "one who habitually wastes energy in regretting any choice made: belatedly but wistfully he sighs over the attractive alternative rejected". Thompson also says that when introducing the poem in readings, Frost would say that the speaker was based on his friend Edward Thomas. In Frost's words, Thomas was "a person who, whichever road he went, would be sorry he didn't go the other".
Regarding the "sigh" that is mentioned in the last stanza, it may be seen as an expression of regret or of satisfaction, but there is significance in the difference between what the speaker has just said of the two roads, and what he will say in the future. According to biographer Lawrence Thompson, as Frost was once about to read the poem, he commented to his audience, "You have to be careful of that one; it's a tricky poem -- very tricky," perhaps intending to suggest the poem's ironic possibilities. A New York Times Sunday book review on Brian Hall's 2008 biography Fall of Frost states: "Whichever way they go, they're sure to miss something good on the other path."