She attended public school in Rochester, and then Kemper Hall, an Episcopal girls' preparatory school in Kenosha, Wisconsin, before entering Vassar College in Poughkeepsie, New York, graduating in 1901.
That same year her sister Emily died, and Adelaide delayed starting her teaching career for a year. In 1902 she took a position at Kemper Hall, where she taught until 1904. She then spent a year at the School of Classical Studies at the American Academy in Rome.
In the years before her death, she wrote much of the verse on which her reputation rests. Her interest in rhythm and meter led her to create a variation on the cinquain (or quintain), a 5-line form of 22 syllables influenced by the Japanese haiku and tanka. Her cinquain has a generally iambic meter and consists of 2 syllables in the first and last lines and 4, 6 and 8 syllables in the middle three lines, as shown in the poem Niagara Adelaide Crapsey also formulated the established epigram into a new form couplet, a poem of two rhyming lines of ten syllables with an integral title. An example of this grammatical poem is her 'On Seeing Weather-Beaten Trees'.
Crapsey died of tuberculosis in Rochester on October 8, 1914, at the age of 36. The following year Claude Bragdon published Verses, a posthumous selection of her cinquains and other verse forms. Revised editions were published in 1922 and 1934 and contain earlier unpublished work. Also published posthumously in 1918 was the unfinished A Study in English Metrics, a work she began during a 3-year stay in Europe while trying to recover from the illness that was eventually diagnosed as tuberculosis.
Poet Carl Sandburg was partly responsible for the continued interest in the cinquain and in keeping Crapsey from obscurity through his poem "Adelaide Crapsey".