Although the doctrine and work of the Holy Spirit is no longer being ignored in theology (as was often the case in centuries past), the authority of the Spirit remains essentially undefined. The need for such a definition, however, is urgent. Some dangerous trends in the contemporary understanding of the Spirit have developed (trends that can only be exposed through careful exegesis of Scripture and theological clarification). Indeed, some contemporary models often leave us with a nonauthoritative "Spirit" predisposed toward universalism, experientialism, or panentheism. This work will attempt to show that the nature of the Holy Spirit's authority can be clearly defined through biblical and systematic theology. When we investigate the Spirit's place within the pattern of divine authority, as specified in Scripture, we discover that the Holy Spirit indeed possesses a unique authority as divine Person, Christ's Executor, Teacher, and Governor of the Church. Such a work will be helpful for both the theologian and the pastor. First, definitions of the Spirit's authority will be developed through historical, exegetical, and theological analysis. Then these definitions will be applied to specific church practices, including hermeneutics, church structure and guidance, and Christian spirituality. A response will also be given to those "practical theologies" that are subtly diminishing the Spirit's authority in relation to the contemporary church.