A long and interesting introductory essay starts from the proposition that the poets included should be all the 'good' ones (implicitly the field is Anglo-Irish poetry, though notably a few Indian poets are there) active since Tennyson's death. In fact the poets chosen by Yeats are a notably idiosyncratic selection to represent modern verse. The Victorians are much represented, while the war poets from World War I are not. The modernist tendency does not predominate, though it is not ignored; Georgian poetry is covered quite thoroughly, while a Dublin wit like Oliver St. John Gogarty is given much space and praised in the introduction as a great poet.
Yeats was influenced by his personal feelings; Gogarty was a personal friend. Yeats also included poems by Margot Ruddock, with whom he was having a relationship, and other friends such as Shri Purohit Swami. He notes that Rudyard Kipling and Ezra Pound are under-represented because paying their royalties would have cost too much. People have regretted that he did not say which poems he would have added given a free hand.