Using a reactive software product line approach, Salion made the transition to software product lines with 2 person-months of effort, the equivalent of 1% of the effort required to build its baseline enterprise software product. This is two orders-of-magnitude less than the effort typically reported with proactive software product line transition efforts. Since the transition, Salion has achieved 90-day time-to-market intervals for seven new commercial products in its software product line, with each new product deployment requiring only 10% of the effort required to build its baseline enterprise software product. This report summarizes Salion’s experience with a reactive software product line approach, some of the unique contributions of the experience, and generalizations that characterize how other organizations may benefit from reactive product line techniques.