This project studies the retrieval of the concept of mystery in the movement of biblical, liturgical, and patristic renewal known as the twentieth century Ressourcement. In particular, it explores the spiritual dimensions of a liturgical theology of mystery. It argues that the concept of mystery serves as a bridge between the liturgy and the wider life of the Church, especially the ascetical and mystical aspects of spiritual theology. After first introducing the roots of a rediscovery of mystery in the nineteenth and twentieth centuries and surveying the pioneering work of Odo Casel, it details the integration between liturgy and the spiritual life in two major sections. The first part analyzes and synthesizes the interrelation and intrinsic unity between the bible, liturgy, and spirituality in the work of Louis Bouyer. It proceeds by examining how Bouyer deepens the spiritual implications of Casel's insights through a robust biblical theology of the Word, such that Bouyer's vision can be seen as following the dynamic Word-mystery-liturgy-spirituality along an unbroken continuity. It then uses insights from the Schmemann-Kavanagh-Fagerberg-Taft school of liturgical theology to illustrate how Bouyer unites asceticism and mysticism with liturgy around an integrative, multifaceted vision of the Christian mystery. The second part studies the contribution of mystery to a liturgical spirituality in the additional voices of Columba Marmion, Alexander Schmemann, and Jean Corbon. They complement Bouyer's account by situating mystery in the context of a monastic vision of the spiritual life and showing its affinity with the Trinitarian, pneumatic, and eschatological liturgical vision of Eastern Christianity. This project observes that the concept of mystery is inextricably tied to the concept of union with God, understood in various ways as divinization, divine adoption, and recapitulation. It concludes that mystery is an integrative, synthetic, participatory, and transformative concept that is capable of renewing the spiritual and liturgical life of the Church in every age.