This work tackles another Marian topic that was left unresolved at the conclusion of Second Vatican Council, namely, Mary’s mediation of the grace of the sacraments. This work is partly apologetic, partly catechetical but mostly theological. The inquiry also identifies departures from Catholic teaching by non-Catholic Christian denominations which may serve the interests of the Church’s efforts directed to Christian unity and Catholic evangelization. In a slight departure from accepted scholarly approaches to systematic theology, this investigation introduces the mystical revelations of the Blessed Anne Catherine Emmerich and the Venerable Sister Mary of Agreda in support of the argument that Mary mediates the grace of the sacraments ex opere operantis, helping to make a person more disposed to the worthy reception of the sacraments of charity so they become living sacraments of love.