diff --git a/NAMESPACE b/NAMESPACE
index b84fb841f..9ffcdf950 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -155,6 +155,8 @@ export(renderLeaflet)
 export(safeLabel)
 export(scaleBarOptions)
 export(setMaxBounds)
+export(setStyle)
+export(setStyleFast)
 export(setView)
 export(showGroup)
 export(tileOptions)
diff --git a/R/methods.R b/R/methods.R
index d394ae1aa..408d7c52e 100644
--- a/R/methods.R
+++ b/R/methods.R
@@ -32,6 +32,31 @@ setView <- function(map, lng, lat, zoom, options = list()) {
   )
 }
 
+#' Efficiently style a group that has already been added to the map
+#'
+#' Call with a group and a vector of style lists of length N. The first N
+#' features of the group will be restyled.
+#'
+#' @examples
+#' \donttest{
+#' renderLeaflet("map", {
+#'   leaflet() %>% addPolygons(data = zones, group = "zones", color = "red")
+#' })
+#' colour = "blue"
+#' styles = lapply(pal(values), function(colour) {list(fillColor=colour, color=colour)})
+#' leafletProxy("map") %>%
+#'   setStyle("zones", styles)
+#' }
+#' @export
+setStyle = function(map, group, styles, label = NULL, offset = 0) {
+    invokeMethod(map, NULL, "setStyle", group, styles, label, offset - 1)
+}
+
+#' @export
+setStyleFast = function(map, group, color = NULL, weight = NULL, label = NULL, stroke = NULL, fill = NULL) {
+    invokeMethod(map, NULL, "setStyleFast", group, color, weight, label, stroke, fill)
+}
+
 #' @describeIn map-methods Flys to a given location/zoom-level using smooth pan-zoom.
 #' @export
 flyTo <- function(map, lng, lat, zoom, options = list()) {
diff --git a/inst/htmlwidgets/leaflet.js b/inst/htmlwidgets/leaflet.js
index 3d0104a49..21cf16342 100644
--- a/inst/htmlwidgets/leaflet.js
+++ b/inst/htmlwidgets/leaflet.js
@@ -655,7 +655,13 @@ _htmlwidgets2.default.widget({
               _shiny2.default.onInputChange(map.id + "_click", {
                 lat: e.latlng.lat,
                 lng: e.latlng.lng,
-                ".nonce": Math.random() // Force reactivity if lat/lng hasn't changed
+                ".nonce": Math.random(), // Force reactivity if lat/lng hasn't changed
+                modifiers: {
+                  alt: e.originalEvent.altKey,
+                  ctrl: e.originalEvent.ctrlKey,
+                  meta: e.originalEvent.metaKey,
+                  shift: e.originalEvent.shiftKey
+                }
               });
             });
 
@@ -1282,6 +1288,61 @@ function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { de
 var methods = {};
 exports.default = methods;
 
+/** Much more performant way to style loaded geometry */
+
+methods.setStyle = function (group, styles, labels) {
+  var offset = arguments.length <= 3 || arguments[3] === undefined ? 0 : arguments[3];
+
+  window.map = this;
+  var layers = this.layerManager.getLayerGroup(group).getLayers();
+
+  if (styles) {
+    for (var i = 0; i < styles.length; i++) {
+      layers[i + offset].setStyle(styles[i]);
+    }
+  }
+  if (labels) {
+    for (var _i = 0; _i < styles.length; _i++) {
+      layers[_i + offset].bindTooltip(labels[_i]);
+    }
+  }
+};
+
+/** Much more performant way to style loaded geometry */
+methods.setStyleFast = function (group, colors, weights, labels, strokes, fills) {
+  window.map = this;
+  var layers = this.layerManager.getLayerGroup(group).getLayers();
+
+  if (labels) {
+    for (var i = 0; i < labels.length; i++) {
+      layers[i].bindTooltip(labels[i]);
+    }
+  }
+
+  if (colors) {
+    for (var _i2 = 0; _i2 < colors.length; _i2++) {
+      layers[_i2].setStyle({ color: colors[_i2], fillColor: colors[_i2] });
+    }
+  }
+
+  if (weights) {
+    for (var _i3 = 0; _i3 < weights.length; _i3++) {
+      layers[_i3].setStyle({ weight: weights[_i3] });
+    }
+  }
+
+  if (strokes) {
+    for (var _i4 = 0; _i4 < strokes.length; _i4++) {
+      layers[_i4].setStyle({ stroke: strokes[_i4] });
+    }
+  }
+
+  if (fills) {
+    for (var _i5 = 0; _i5 < fills.length; _i5++) {
+      layers[_i5].setStyle({ fill: fills[_i5] });
+    }
+  }
+};
 
 function mouseHandler(mapId, layerId, group, eventName, extraInfo) {
   return function (e) {
@@ -1297,7 +1358,13 @@ function mouseHandler(mapId, layerId, group, eventName, extraInfo) {
     }
     var eventInfo = _jquery2.default.extend({
       id: layerId,
-      ".nonce": Math.random() // force reactivity
+      ".nonce": Math.random(), // force reactivity
+      modifiers: {
+        alt: e.originalEvent.altKey,
+        ctrl: e.originalEvent.ctrlKey,
+        meta: e.originalEvent.metaKey,
+        shift: e.originalEvent.shiftKey
+      }
     }, group !== null ? { group: group } : null, latLng, extraInfo);
 
     _shiny2.default.onInputChange(mapId + "_" + eventName, eventInfo);
diff --git a/javascript/src/index.js b/javascript/src/index.js
index 3230ec298..711ac4efd 100644
--- a/javascript/src/index.js
+++ b/javascript/src/index.js
@@ -140,7 +140,13 @@ HTMLWidgets.widget({
             Shiny.onInputChange(map.id + "_click", {
               lat: e.latlng.lat,
               lng: e.latlng.lng,
-              ".nonce": Math.random() // Force reactivity if lat/lng hasn't changed
+              ".nonce": Math.random(), // Force reactivity if lat/lng hasn't changed
+              modifiers: {
+                alt: e.originalEvent.altKey,
+                ctrl: e.originalEvent.ctrlKey,
+                meta: e.originalEvent.metaKey,
+                shift: e.originalEvent.shiftKey
+              }
             });
           });
 
diff --git a/javascript/src/methods.js b/javascript/src/methods.js
index 5cbc7c3e6..91c326b76 100644
--- a/javascript/src/methods.js
+++ b/javascript/src/methods.js
@@ -13,6 +13,58 @@ import Mipmapper from "./mipmapper";
 let methods = {};
 export default methods;
 
+/** Much more performant way to style loaded geometry */
+methods.setStyle = function(group, styles, labels, offset = 0) {
+  window.map = this;
+  let layers = this.layerManager.getLayerGroup(group).getLayers();
+
+  if (styles) {
+    for (let i = 0; i < styles.length; i++) {
+      layers[i + offset].setStyle(styles[i]);
+    }
+  }
+  if (labels) {
+    for (let i = 0; i < styles.length; i++) {
+      layers[i + offset].bindTooltip(labels[i]);
+    }
+  }
+};
+
+/** Much more performant way to style loaded geometry */
+methods.setStyleFast = function(group, colors, weights, labels, strokes, fills) {
+  window.map = this;
+  let layers = this.layerManager.getLayerGroup(group).getLayers();
+
+  if (labels) {
+    for (let i = 0; i < labels.length; i++) {
+      layers[i].bindTooltip(labels[i]);
+    }
+  }
+
+  if (colors) {
+    for (let i = 0; i < colors.length; i++) {
+      layers[i].setStyle({color: colors[i], fillColor: colors[i]});
+    }
+  }
+
+  if (weights) {
+    for (let i = 0; i < weights.length; i++) {
+      layers[i].setStyle({weight: weights[i]});
+    }
+  }
+
+  if (strokes) {
+    for (let i = 0; i < strokes.length; i++) {
+      layers[i].setStyle({stroke: strokes[i]});
+    }
+  }
+
+  if (fills) {
+    for (let i = 0; i < fills.length; i++) {
+      layers[i].setStyle({fill: fills[i]});
+    }
+  }
+};
 
 function mouseHandler(mapId, layerId, group, eventName, extraInfo) {
   return function(e) {
@@ -29,7 +81,13 @@ function mouseHandler(mapId, layerId, group, eventName, extraInfo) {
     let eventInfo = $.extend(
       {
         id: layerId,
-        ".nonce": Math.random()  // force reactivity
+        ".nonce": Math.random(),  // force reactivity
+        modifiers: {
+          alt: e.originalEvent.altKey,
+          ctrl: e.originalEvent.ctrlKey,
+          meta: e.originalEvent.metaKey,
+          shift: e.originalEvent.shiftKey
+        }
       },
       group !== null ? {group: group} : null,
       latLng,
diff --git a/man/setStyle.Rd b/man/setStyle.Rd
new file mode 100644
index 000000000..24af1cd15
--- /dev/null
+++ b/man/setStyle.Rd
@@ -0,0 +1,23 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/methods.R
+\name{setStyle}
+\alias{setStyle}
+\title{Efficiently style a group that has already been added to the map}
+\usage{
+setStyle(map, group, styles, label = NULL, offset = 0)
+}
+\description{
+Call with a group and a vector of style lists of length N. The first N
+features of the group will be restyled.
+}
+\examples{
+\donttest{
+renderLeaflet("map", {
+  leaflet() \%>\% addPolygons(data = zones, group = "zones", color = "red")
+})
+colour = "blue"
+styles = lapply(pal(values), function(colour) {list(fillColor=colour, color=colour)})
+leafletProxy("map") \%>\%
+  setStyle("zones", styles)
+}
+}