When Walt Disney began to develop a film based on the novel, Bill Peet originally wrote a version that was set to be darker and slightly closer to the source material, but many changes were made, including Baloo's personality, which was changed into a fun-loving, humble personality.

In the book, Baloo was a humorless, serious, and strict aging sloth bear who utilized militant discipline while mentoring Mowgli and the wolf cubs. In the original book by Rudyard Kipling, Baloo was very different from his Disney incarnation.