This book contains a study and breakdown of "harmony in 4ths". The introduction of quartal harmony in modern jazz began in the 1960's. Compositions by Miles Davis and John Coltrane such as "Impressions" and "So What" showcased chord voicings derived from quartal harmony. The purpose of this book is to show guitarists how to function in an area of harmony mostly dominated by keyboard players. Common uses of quartal harmony are demonstrated and analyzed. Exercises and compositions in the style of Wayne Shorter, Herbie Hancock and others are included. Online audio contains demonstrations of all exercises.