The Service for the Lord's Day describes the general format or ordering of worship in the Presbyterian Church (U.S.A). The creation of the service for the Lord's Day was one of the most positive contributions of the Worship Book of 1970. The Presbyterian Supplemental Liturgical Resource (SLT) series includes liturgies that were used on a trial basis in preparation for the development of the Book of Common Worship. Though superseded by the Book of Common Worship, SLR resources remain valuable, both for the variety of liturgical texts they contain and for the commentary on the text, which contains rich historical, theological, and practical background.