The Preaching the Word commentary series, published by Crossway, is an exposition-focused Bible study resource that reflects Reformed theology.
Volumes in the series are known for their accessible explanations of the biblical text and for their helpfulness to expository preachers. 
The Series Editor, R. Kent Hughes, was the pastor of College Church in Wheaton, Illinois, for 27 years. Since 2015 he has been a professor at Westminster Theological Seminary. 
Hughes authored the first commentaries in this series in 1989 and has contributed more than 10 volumes to date.
Currently, there are 36 volumes in the Preaching the Word series covering 41 books of the Bible. There are projected to be 50 volumes when the series is complete.
Preaching the Word commentaries are not technical making them easy to understand for readers who do not have training in the original languages of Scripture.
Authors approach the text passage-by-passage, but they also take time to discuss individual verses, and even single words, when they are important to understanding the message of the biblical writer.
The authors in the Preaching the Word series have themselves preached through the books they are writing about, so the expositional insights come from firsthand experience in the pulpit. 
Please see how the Preaching the Word series compares to dozens of other commentary series on the Bible Commentaries Comparison Chart.
Preaching the Word Commentaries: Reviews
Theologian D.A. Carson writes,
“There is a long history of informed, edifying biblical expositions that have been mightily used of God to shape and strengthen the church. These volumes admirably fit this tradition.”
While Carson and others have praised the series as a whole, a few volumes have been especially well-reviewed.
Hughes’ Mark volumes is considered one of the best Mark commentaries, having received the ECPA Gold Medallion Book Award for best commentary in 1990.
Philip Graham Ryken’s Exodus volume is another example, as its often rated as one of the best Exodus commentaries.
Robert W. Yarbrough, Professor of New Testament, Covenant Theological Seminary, praised Douglas Sean O’Donnell’s Matthew volume as one of the best Matthew commentaries:
“This commentary grows out of wide reading and solid learning—the footnotes alone are a gold mine. O’Donnell writes with a zest for real life, wit, and (controlled) whimsy. The outcome: sermons that both revel in Christ and reveal Christ in fresh and striking ways.
The author proves to be a hard-working and natural expositor of Scripture. This book goes to the top of my list of sterling homiletical commentaries on the first Gospel.”
Interviews from the Preaching the Word Series on Best Bible Commentaries
I was pleased to conduct a question-and-answer interview with Pastor O’Donnell. Please follow this link to read the full Q & A: Matthew – Douglas Sean O’Donnell
Preview of Q&A: As a pastor and scholar, my goal is to demonstrate and declare, in Peter’s language, the “excellencies” of Christ (1 Peter 2:9). With every section of Matthew’s Gospel, I encountered the incarnate and resurrected Jesus. I was taken aback. Reformed. Renewed. Edified. Encouraged. Stunned. Changed. Face down in adoration.
New Testament Volumes
The links below go to Amazon, which sells new and used copies.
The Sermon on the Mount: The Message of the Kingdom – R. Kent Hughes | Published: 2001
Matthew: All Authority in Heaven and on Earth – Douglas Sean O’Donnell | Published: 2013
Mark: Jesus, Servant and Savior Vols. 1 and 2 – R. Kent Hughes | Published: 1989
Luke: That You May Know the Truth, Vol. 1 – R. Kent Hughes | Published: 1998
Luke: That You May Know the Truth, Vol. 2 – R. Kent Hughes | Published: 1998
John: That You May Believe – R. Kent Hughes | Published: 1999
Acts: The Church Afire – R. Kent Hughes | Published: 1996
Romans: Righteousness From Heaven – R. Kent Hughes | Published: 1991
1 Corinthians: The Word of the Cross – Stephen T. Um | Published: 2015
2 Corinthians: Power in Weakness – R. Kent Hughes | Published: 2006
Galatians: Gospel-rooted Living – Todd A. Wilson | Published: 2013
Ephesians: The Mystery of the Body of Christ – R. Kent Hughes | Published: 1990
Philippians: The Fellowship of the Gospel – R. Kent Hughes | Published: 2007
Colossians and Philemon: The Supremacy of Christ – R. Kent Hughes | Published: 1989
1 & 2 Thessalonians: The Hope of Salvation – James H. Grant Jr. | Published: 2011
1 & 2 Timothy and Titus: To Guard the Deposit – R. Kent Hughes and Bryan Chapell | Published: 2000
Hebrews: An Anchor for the Soul Vols. 1 and 2 – R. Kent Hughes | Published: 1993
James: Faith That Works – R. Kent Hughes | Published: 1991
1 & 2 Peter and Jude: Sharing Christ’s Sufferings – David Helm | Published: 2008
1–3 John: Fellowship in God’s Family – David L. Allen | Published: 2013
Revelation: The Spirit Speaks to the Churches – James M. Hamilton Jr. | Published: 2012
Old Testament Volumes
Genesis: Beginning and Blessing – R. Kent Hughes | Published: 2004
Exodus: Saved for God’s Glory – Philip Graham Ryken | Published: 2005
Leviticus: Holy God, Holy People – Kenneth A. Mathews | Published: 2009
Numbers: God’s Presence in the Wilderness – Iain M. Duguid | Published: 2006
Deuteronomy: Loving Obedience to a Loving God – Ajith Fernando | Published: 2012
Joshua: People of God’s Purpose – David Jackman | Published: 2014
Judges and Ruth: God in Chaos – Barry Webb | Published: 2015
1 Samuel: Looking for a Leader – John Woodhouse | Published: 2002
2 Samuel: Your Kingdom Come – John Woodhouse | Published: 2015
Job: The Wisdom of the Cross – Christopher Ash | Published: 2014
The Psalms Volume 1, 1–41: Rejoice, the Lord Is King – James A. Johnston | Published: 2015
Proverbs: Wisdom that Works – Raymond C. Ortlund Jr. | Published: 2012
Ecclesiastes: Why Everything Matters – Philip Graham Ryken | Published: 2010
The Song of Solomon: An Invitation to Intimacy – Douglas Sean O’Donnell | Published: 2012
Isaiah: God Saves Sinners – Raymond C. Ortlund Jr. | Published: 2005
Jeremiah and Lamentations: From Sorrow to Hope – Philip Graham Ryken | Published: 2001
Daniel: The Triumph of God’s Kingdom – Rodney Stortz | Published: 2004