When the Spirit Says Sing! tells the fascinating story of spirituals and their relationship to enslaved people of the United States, the Bahamas, and Mexico. It begins with the voyage from Africa as it explores the earliest remnants of African song, surviving in America as the ring shout, native to South Carolina and Georgia.

Most of the spirituals mentioned in the book, including ring shouts, are accompanied by printed lyrics and suggestions for listening on the web. Performers recommended for listening include Kathleen Battle, Mahalia Jackson, Paul Robeson, Bruce Springsteen, Joan Baez, the Fisk Jubilee Singers, and Moses Hogan.

The book covers a wide range of topics, including slave arrivals from Africa, the Underground Railroad, codes and symbols in spirituals, the development of different styles, and the relationship between religion and slavery in the South. The author also describes the roles of abolitionists, stationmasters, and conductors on the Underground Railroad. Each of the abovementioned is accompanied by the depiction of at least one, and usually several, relevant spirituals.

When the Spirit Says Sing! celebrates spirituals as a compelling expression of art and culture. Those with little knowledge of this music will find themselves informed, and those well acquainted with it will find new material to explore. It delves deeply and comprehensively into the role of singing in the lives of enslaved people and is accessible to both novices and scholars.