"Jockey Young'uns: The Legend of the Kentucky Derby's Youngest Winners" is a children's book that tells the inspiring stories of Alonzo "Lonnie" Clayton and James "Soup" Perkins, two Black jockeys who achieved great success and faced challenges in the world of horseracing during the late 19th and early 20th centuries. The book provides a glimpse into their lives, their dedication to their craft, and the racial discrimination they encountered.

The story begins with the historic Kentucky Derby race in 1875, where the first winner, Aristides, was ridden by Oliver Lewis, a Black jockey. This sets the stage for the achievements and struggles that Lonnie Clayton and Soup Perkins would later experience.

Lonnie Clayton, born in Mississippi, comes from a large family and helps support them from a young age. He leaves home at twelve to work at a stud farm, where he learns to ride and eventually becomes a jockey. Lonnie's determination and talent led him to win the Kentucky Derby at the age of fifteen, making him the youngest jockey to achieve this feat at the time.

Soup Perkins, growing up in Kentucky, starts working with horses at a young age and becomes a jockey at eleven. He earns a reputation for his skill and connection with horses, winning multiple races and capturing the Kentucky Derby at fifteen, tying with Lonnie as the youngest winner.

The book highlights the challenges faced by Black jockeys during this era. It mentions the Union of White Jockeys, a group formed to exclude Black jockeys from racing, driven by racial discrimination and a desire to claim all prize money for white riders. Lonnie and Soup faced hostility, racism, and efforts to impede their careers, but they remained resilient in pursuing their dreams.

The narrative explores Lonnie's financial success, which enabled him to invest in properties and become a businessman. However, he faced a decline due to ongoing racism and legal troubles. Soup's career was abruptly halted when he was disqualified from a race and suspended from the sport. He eventually transitions to training horses and continues his work in Canada.

The book concludes by summarizing the lives and legacies of Lonnie Clayton and Soup Perkins. It also provides a glossary, a timeline of significant events, and background information about the Kentucky Derby and the Union of White Jockeys.