Why migrate your control system now? Legacy Systems are hard to maintain… • They have limited spare parts (and failures increase…) • The run on old PC hardware and operating systems • They provide limited communications and diagnostics • And the people who know them are retiring! A migration to a modern, sustainable control system will provide new tools to connect to new systems that provide benefits in addition to reliability and parts availability. Their open communications architecture allows for easier connectivity to Historians, Advanced Control, MES for PlantPAx. This presentation covers the questions asked, migration strategies and risks, and steps that are needed for a control system migration. Two case studies with different approaches are described and the results summarized.