English composer and musician John Wilson (1595-1674) collaborated with poet Thomas Stanley in publishing Psalterium Carolinum (London, 1657). The musical settings in the collection commemorate the legacy of King Charles I who was executed for treason in January 1649. The Psalterium was part of a Royalist propaganda effort aimed at positively refashioning the dead king’s reputation. The present essay is a critical musical edition and commentary on this work. The edition is based upon microfilm copies of the 1657 edition of the Psalterium housed in the British Library in London. The edition includes an editorial policy explaining the decisions made in creating the edition, and a critical report that records particular corrections to the original in terms of pitch, rhythm and text treatment. The accompanying commentary provides a biographical sketch of John Wilson, explains his importance as performer and composer, and compares the style and scoring of the Psalterium to other contemporary genres. Most significantly, the commentary identifies the Psalterium as a collection of psalm-like pieces and connects it directly to the ongoing propaganda campaign that sought to restore Charles I’s legacy and prompt a national initiative for the restoration of the English crown.