A thermoplastic vulcanizate composition includes (A) greater than 15 wt % of a block composite that has (i) an ethylene/alpha-olefin/diene interpolymer in which the alpha-olefin is an alpha olefin monomer having from 3 to 10 carbon atoms and the diene is a diene monomer having from 2 to 25 carbon atoms, (ii) a propylene based polymer, and (iii) a block copolymer comprising a soft block and a hard block in which the soft block has the same composition as the ethylene/alpha-olefin/diene polymer and the hard block has the same composition as the propylene based polymer; and (B) a remainder of a curative system and optionally at least one of a vulcanizable elastomer, a thermoplastic polyolefin, and an oil.