We　propose　a　scheme　for　generation　of　SU(2)　coherent　states　for　an　atomic　ensemble　and　a　cavity　mode.　In　the　scheme　a　collection　of　two-level　atoms　resonantly　interact　with　a　single-mode　quantized　field.　Under　certain　conditions,　the　system　can　evolve　from　a　Fock　state　to　a　highly　entangled　SU(2)　coherent　state.　The　operation　speed　increases　as　the　number　of　atoms　increases,　which　is　important　in　view　of　decoherence.　©　2009　Chinese　Physical　Society　and　IOP　Publishing　Ltd.