This book explores the theological and textual connections among ancient and modern epicleses, primarily through analysis of a selection of epicletic texts in contemporary Western eucharistic prayers and the theological principles that shaped them. Liturgical scholarship on the Spirit's role in early liturgical prayers and texts conducted during the twentieth century contributed to the language and pneumatology of contemporary eucharistic prayers in the Western Christian tradition. More recent considerations of these ancient sources suggest ways to articulate and incorporate a more expansive understanding of the connections between the Holy Spirit and the Eucharist into the euchological repertoire of various ecclesial traditions.