Methods for treating Fibrodysplasia Ossificans Progressiva (FOP) are provided. Such methods involve administering to a subject having FOP an effective regime of an activin receptor type 2A (ACVR2A) and/or an activin receptor type 2B (ACVR2B) antagonist or an activin receptor type 1 (ACVR1) antagonist. Antagonists include fusion proteins of one or more extracellular domains (ECDs) of ACVR2A, ACVR2B and/or ACVR1 and the Fc domain of an immunoglobulin heavy chain, and antibodies against ACVR2A, ACVR2B, ACVR1 or Activin A.
