In January of 1996, Intuit?s QuickBooks team was faced with an aging code-base using a custom Mac/Win GUI toolkit, a large and rapidly growing customer base, and a rapidly growing and product-inexperienced engineering team. To increase the product?s quality and feature predictability while retaining its ship date rigidity, we created "Ready-to-Roll" Boxcar Development. The process enabled the defining of each new feature, enhancement, or engineering re-architecture as a set of boxcars on the product train. A "coupled" boxcar was rapidly brought to a supportable level of quality, or "decoupled" for re-evaluation and re-engineering. Frontloading the highest priority boxcars increased predictability of the product train's contents, while the process allowed for greater flexibility with respect to overall content. "Ready-to-Roll" Boxcar Development kept the product within 2-3 weeks of being supportable and shippable. The process focused on individuals and interactions, working software, customer collaboration and responding to change. Better yet, it worked!