The　characteristics　of　stress-induced　martensitic　transformation　in　polycrystalline　TiNi　alloys　under　uniaxial　tensile　stress　were　studied　with　automatic　electron　backscatter　diffraction　in　a　scanning　electron　microscope.　The　results　show　that　the　propagation　of　stress-induced　martensitic　variant　propagates　by　cooperative　and　collective　transformation　across　neighboring　grains.　As　a　result　of　the　transformation　strain/stress　accompanied　with　the　nucleation　of　the　prior-nucleated　martensite　which　can　supply　nucleation　site　and　stress　for　the　neighboring　grains,　martensitic　variant　can　be　triggered　unless　reaching　the　critical　transformation　stress.　This　cooperative　and　collective　transformation　leads　to　the　formation　of　Lüders-like　deformation　bands　in　textured　polycrystalline　TiNi　shape　memory　alloys.　Copyright　©　2008　ASM　International　All　rights　reserved.