The Letters of Catherine of Siena, Volume I: Letters 1–70
Reprinted in 2011
The first volume in the first complete translation of the Epistolario of St. Catherine of Siena (1343-1380) makes available to a large body of readers a major historical and religious document of the Middle Ages. (Also featuring an Introduction and Notes by the translator).
You may also be interested in Catherine of Siena: An Anthology, a 2-volume set published in 2012.
"...follows the highest standards of textual scholarship, and will certainly be the standard English translation; . . . an essential tool . . . of medieval spirituality." —Church History
"Detailed commentaries and textual notes accompany and illumine each letter . . . as well as indices, manuscript lists, maps, a chronology of Cathernine's life, and bibliographies. No other existing volume approaches either the scholarship or the vibrancy of this translation in English." —Theology Today