The remarkable life story of Ella Jenkins, "The First Lady of Children's Music." Ella Jenkins was one of the most influential musicians of the twentieth century. Her songs "You'll Sing a Song and I'll Sing a Song" and "Who Fed the Chickens?" are classics in the world of children's music. In a career spanning more than sixty years, she recorded forty albums, won a lifetime-achievement Grammy, and became the best-selling individual artist in the history of Smithsonian Folkways Records, the independent label that played a significant role in the 1960s folk revival movement and introduced listeners to Woody Guthrie and Pete Seeger. During her remarkable career, Jenkins joined forces with twentieth-century luminaries such as Odetta, Big Bill Broonzy, Armando Peraza, Bayard Rustin, and Fred Rogers. Despite her wide-reaching influence on children's music, Ella Jenkins's sonic civil rights activism isn't widely known today. Based on dozens of interviews and access to Ella Jenkins's personal archives, Gayle F. Wald's This Is Rhythm shares how Jenkins, a "rhythm specialist" with no formal musical training, became the most prolific and significant American children's musician of the twentieth century, creating a beloved catalog of songs grounded in values of community-building, antiracism, and cultural pluralism. Wald traces how the daughter of southern migrants translated the music of her own Black girlhood on the South Side of Chicago into a form of civil rights activism--a musical education that empowered children by introducing them to Black history, African diasporic rhythms, and a participatory, community-centered approach to music. Wald also discusses how, beginning in 1961, Jenkins built a life with a female partner who supported her materially and emotionally. Although Jenkins did not talk publicly about her sixty-three-year relationship, she opened up to Wald, offering insight into how a "private" Black woman in the public eye negotiated sexuality in an era before gay and lesbian liberation movements. Throughout her career, her innovative music found its way into thousands of community centers, classrooms, and concert venues, and her "call-and-response" method has influenced and empowered generations of children and adults. A beautifully written tribute to Ella Jenkins's legacy, this biography illustrates her impact on children's music and expands our understanding of folk music's relationship with social justice. Jenkins used music to build a new world in which children--and adults--are encouraged to listen to each other's distinct rhythms.