Most legacy core software systems are too inflexible, outdated, and brittle to give businesses the flexibility they need to win, serve, and retain customers. Software development leaders want to modernize these applications using cloud-native technologies and practices but are often stymied by the difficulty of the task and unable to even start the journey. Proper scoping, clear objectives, clear timelines, and an embrace of new application development methods can break this logjam and open the way to transform or replace such inflexible apps. This report helps software development leaders plan and launch core-app modernizations using cloud-native services.