"The Spring and the Fall” is comprised of three stanzas with six lines apiece. A stanza with six lines is called a sestet, so the poem is made of three sestets. With a total number of 18 lines, the poem is compact and short, aligning with the lyric genre. Lyrics tend to be brief. The tiny aspect of Millay’s poem matches the "little ways” (Line 12 and 18) that love retreats and breaks the speaker’s heart.

Although the poem has no traditional meter, it possesses a continually melodious sound that makes it read like there’s standard meter present. The playfulness with meter represents Millay’s ability to juggle contemporary poetics and traditional poetry. She nods to tradition with a pleasant-sounding poem while at once rebelling against it by varying the feet—the stresses on the syllables—in the lines. Of course, the poem has a set rhyme scheme. In each stanza, the first two lines rhyme, the middle two lines rhyme, and the last lines rhyme.

The form might relate to the theme of fate and inevitability. The speaker knows that love—like the days and seasons—will leave and return.