Commemorating the fiftieth anniversary of the promulgation of The Roman Missal (1970), With One Spirit embarks on a significant investigation into the history of this text and the principles that impacted its development. In particular, Lamberts examines whether and how The Roman Missal encourages the active participation of the faithful in the liturgy demanded by the Second Vatican Council. Considering this pastoral and theological context, With One Spirit offers a commentary of the possibilities and limitations of the Missal's encouragement of active participation, and formulates suggestions and improvements to realize true communal Eucharistic celebrations.