S&P Global Ratings assigned its 'AA' long-term rating to Massachusetts Development Finance Agency's $500 million tax exempt series 2024T revenue bonds issued for Children?s Hospital of Boston (Children's). At the same time, we affirmed our ratings on the agency's bonds issued for Children's and on Children's taxable debt. The outlook is stable. Securing the bonds is a general obligation from the obligated group--of which Children's is the only member--as well as a guarantee from its parent, Children's Medical Center. Nonobligated entities include employed Harvard Medical School and Children's physicians and various support companies, primarily holding real estate. Bond proceeds will be used for future capital spending. Also incorporated into this analysis are Children's plans to issue another $468.5 million of