Magnesium　anisotropic　behavior　is　enhanced　by　different　deformations　paths　and　modes.　The　mechanical　anisotropy　during　plastic　deformation　of　a　Mg-3Al-1Zn　magnesium　alloy　was　examined　by　uniaxial　compression　(UC)　and　plane　strain　compression　(or　channel-die　CD)　at　room　temperature.　The　mechanical　behavior　and　the　observed　microtextures　were　compared　with　the　predictions　obtained　from　different　crystal　plasticity　models.　A　hot　rolled　AZ31　magnesium　alloy　plate　with　a　strong　basal　texture　was　stressed　along　four　different　directions　to　initiate　different　deformation　mechanisms.　In　both　UC　and　CD,　the　compression　along　the　transverse　direction　generated　mainly　{10-12}　extension　twins,　while　compression　along　the　normal　direction　(Z=ND)　was　initially　accommodated　by　pyramidal　〈c+a〉　slip　followed　by　contraction　twinning.　During　compression　at　45°　of　the　normal　direction　to　the　transverse　direction,　both　slip　and　twinning　took　part　in　the　deformation.　The　sample　compressed　in　CD　along　the　rolling　direction　and　with　the　normal　direction　constrained　was　deformed　by　prismatic　slip　and　tension　twinning.　It　was　found　that　basal　slip　was　an　important　deformation　mechanism　in　all　the　samples.　Simulations　were　made　with　different　models,　and　the　simulated　flow　stresses　were　higher　in　CD　than　that　in　UC,　but　slightly　underestimated　in　case　of　uniaxial　compression.　Modeling　also　corroborated　higher　{10-11}　compression　twinning　activity　in　CD　than　that　in　UC,　and　that　compression　twinning　resulted　in　a　decrease　in　flow　stress　in　CD.　To　fit　with　the　experimental　flow　stresses,　it　was　necessary　to　take　into　account　an　additional　hardening　caused　by　twin　boundaries.　In　our　model,　the　{10-12}　twin　boundaries　were　estimated　to　increase　the　critical　resolved　shear　stress　(CRSS)　of　prismatic　slip　by　about　30%.　However,　twin　induced　hardening　on　pyramidal　〈c+a〉　and　basal　slip　of　about　10%　is　also　necessary　if　contraction　twinning　do　not　soften　the　material.　©　2014　Elsevier　B.V.