There is a Facebook Group for Miraculous Medal Prayer. They have over 2,700 members.

From their About section:

Is there a prayer group in your neighborhood?
Start a Prayer Group of the Miraculous Medal, for Mary to intercede before the Lord for the sick and the most needy. The Lord says: “For where two or three are gathered in my name, there I am with them.” Matthew 18:20. Publish prayer requests for the groups, thanks for favors received, prepare daily prayers, and start a group praying the Angelus or the Holy Rosary. Blessings!

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