A rough outline of the book of Psalms

Book 1 (Psalm 1-41) – Psalms of David – God rescues his people

Book 2 (Psalm 42-72) – The experience of God’s people, the rescue of people from their enemies through his King

Book 3 (Psalm 73-89) – Trust in God through the pain of exile

Book 4 (Psalm 90-106) – God is still king over the world

Book 5 (Psalm 107-150) – The return from exile and waiting for the true king

Taken from: The Psalms Volume 1 – Psalms 1-41, Rejoice the Lord is King by James Johnston p.19-22