Logic to impose a maximum number of checked inputs (two in this demo).
var warning = $(".message"); $("select").multiselect({ header: "Choose only TWO items!", click: function(e){ if( $(this).multiselect("widget").find("input:checked").length > 2 ){ warning.addClass("error").removeClass("success").html("You can only check two checkboxes!"); return false; } else { warning.addClass("success").removeClass("error").html("Check a few boxes."); } } });