Thomas Wyatt (1504?-42) may have written the first sonnet in English. His translation from Plutarch's 'Moralia' was the first publication of a classical moral essay in English. He introduced continental forms such as 'ottava rima' to the language, and his paraphrase of the 'Penitential Psalms' sparked a century of popular psalm translations. Yet while decades of criticism have centered on a handful of his best-known poems, many others are poorly understood, in part because we lack an authoritative edition. This volume—the first in a planned two-volume collection of Wyatt's complete works—comprises scholarly editions of 35 letters or memoranda, Wyatt's 'Declaration from the Tower' and his 'Defence' speech against treason charges. It also includes the first scholarly edition of 'The Quyete of Mynde'. Each text is extensively annotated, each letter has a prefacing headnote, and each grouping of texts is separately introduced. The recipient of one letter is identified here for the first time from new archival discoveries. Two letters of instruction from Henry VIII are included along with four appendices containing related documents. Biographical entries (totalling 17,000 words) identify and introduce 64 persons related to Wyatt's diplomatic service, including every known member of Wyatt's diplomatic household.