We　investigate　the　relation　between　firm　performance　and　boardroom　gender　diversity　using　quantile　regression　methods.　Using　annual　data　on　over　3000　US　firms　from　2007　to　2014,　we　show　that　the　presence　of　women　on　the　board　has　a　positive　effect　on　firm　performance,　and　this　effect　varies　at　different　parts　of　the　performance　distribution.　Critically,　we　demonstrate　that　the　presence　of　women　directors　alters　the　dispersion　of　firm　performance.　Our　quantile　regression　results　suggest　that　female　directors　have　a　significantly　larger　positive　impact　in　high-performing　firms　relative　to　low-performing　firms.　The　board　gender　diversity　effect　is　not　homogeneous　as　assumed　in　previous　research.　In　addition,　we　account　for　the　endogenous　selection　of　women　to　the　board.　Using　instrumental　variable　quantile　regression,　we　find　that　in　general　there　is　a　positive　correlation　between　firm　performance　and　board　gender　diversity.　Overall,　we　suggest　that　boardroom　gender　diversity　has　an　effect　on　both　the　conditional　mean　and　the　dispersion　of　firm　performance,　and　quantile　regression　adds　value　to　the　empirical　examination　of　the　performance　impact　of　board　gender　diversity.　(C)　2017　Elsevier　Inc.　All　rights　reserved.