The Psalms have a double identity. They are scripture and liturgy. They compose a book of the Bible and are found in our hymnals and books of worship and prayer. When we think of them in historical perspective, another identity emerges. They are the liturgical poetry of ancient Israel, texts with a history of composition and use before they became scripture. A commentary in this Interpretation series needs to keep all three identities in view. That puts some strain on the commentator's task. The attempt to interpret the Psalms in awareness of the depth in their identity explains some things about the commentary and its writing. - Preface.