Bala Kanda is one of the two books, along with the epic's final Uttara Kanda, that most critical scholars regard as later additions to what was likely an originally five-book poem running from Ayodhya Kanda through Yuddha Kanda, a judgment based on differences in style and vocabulary, on this book's explicit, sustained framing of Rama as a full divine incarnation of Vishnu, a status the core narrative books tend to treat more ambiguously, letting Rama act and grieve as fully human for most of the story, and on narrative details that sit awkwardly alongside the core books' own account of certain events. This does not mean the book is a late fabrication with no old material behind it, since much of its content, including the swayamvara contest and Vishwamitra's forest mission, likely draws on older story elements that were shaped into their current framing form when the book was composed or expanded to introduce the epic's core narrative more fully.
The tradition's own account of authorship is more layered than a single human poet: Valmiki, revered as the adi-kavi or first poet of Sanskrit verse, is said to have received the poem's meter directly from the god Brahma after witnessing a hunter kill one of a pair of mating birds, his spontaneous grief crystallizing into the first shloka, the poetic meter the entire epic subsequently follows.