Some Christians emphasize doctrine, others experience. Martyn Lloyd-Jones emphasized both. Marrying a Reformed understanding of biblical theology to a passionate desire for a deeper experience of God, he urged all Christians to seek baptism with the Holy Spirit. This he viewed as a direct sealing of the assurance of God's love to a believer's consciousness which results in a heightened awareness of God, brings joy to worship, and adds a new dimension to the church's witness. This book examines the sources of Dr Lloyd-Jones's teaching in the writings of the Puritans and later theologians such as Jonathan Edwards, and compares it with others views of the work of the Holy Spirit which are currently held. It is an important contribution to the ongoing debate.