diff --git a/common/changes/@uifabric/utilities/detailsheader-fix_2018-03-21-00-31.json b/common/changes/@uifabric/utilities/detailsheader-fix_2018-03-21-00-31.json
new file mode 100644
index 0000000000000..0549f5c0b1130
--- /dev/null
+++ b/common/changes/@uifabric/utilities/detailsheader-fix_2018-03-21-00-31.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "@uifabric/utilities",
+      "comment": "EventGroup.raise: event args are now correctly mixed into the event object.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@uifabric/utilities",
+  "email": "dzearing@microsoft.com"
+}
\ No newline at end of file
diff --git a/common/changes/office-ui-fabric-react/detailsheader-fix_2018-03-21-00-31.json b/common/changes/office-ui-fabric-react/detailsheader-fix_2018-03-21-00-31.json
new file mode 100644
index 0000000000000..076b42db5092a
--- /dev/null
+++ b/common/changes/office-ui-fabric-react/detailsheader-fix_2018-03-21-00-31.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "office-ui-fabric-react",
+      "comment": "DetailsList: headers now resize correctly and respect maxWidth.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "office-ui-fabric-react",
+  "email": "dzearing@microsoft.com"
+}
\ No newline at end of file
diff --git a/packages/office-ui-fabric-react/src/components/DetailsList/DetailsHeader.test.tsx b/packages/office-ui-fabric-react/src/components/DetailsList/DetailsHeader.test.tsx
new file mode 100644
index 0000000000000..de79f7f7e6add
--- /dev/null
+++ b/packages/office-ui-fabric-react/src/components/DetailsList/DetailsHeader.test.tsx
@@ -0,0 +1,89 @@
+import * as React from 'react';
+import { DetailsHeader } from './DetailsHeader';
+import { DetailsListLayoutMode, IColumn } from './DetailsList.types';
+import { Selection, SelectionMode } from '../../utilities/selection/index';
+import { EventGroup, createRef } from '../../Utilities';
+import { mount } from 'enzyme';
+import * as renderer from 'react-test-renderer';
+
+const _items: {}[] = [];
+const _selection = new Selection();
+const _columns: IColumn[] = [
+  { key: 'a', name: 'a', fieldName: 'a', minWidth: 200, maxWidth: 400, calculatedWidth: 200, isResizable: true },
+  { key: 'b', name: 'b', fieldName: 'a', minWidth: 200, maxWidth: 400, calculatedWidth: 200, isResizable: true }
+];
+
+_selection.setItems(_items);
+
+describe('DetailsHeader', () => {
+
+  it('can render', () => {
+    const component = renderer.create(
+      <DetailsHeader
+        selection={ _selection }
+        selectionMode={ SelectionMode.multiple }
+        layoutMode={ DetailsListLayoutMode.fixedColumns }
+        columns={ _columns }
+      />
+    );
+    expect(component.toJSON()).toMatchSnapshot();
+  });
+
+  it('can resize columns', () => {
+    let lastResize = { size: -1, index: -1 };
+
+    const onColumnResized = (
+      column: IColumn,
+      size: number,
+      index: number
+    ): { size: number; index: number; } => lastResize = { size, index };
+    const headerRef = createRef<any>();
+
+    const columns = [];
+    const wrapper = mount(
+      <DetailsHeader
+        componentRef={ headerRef }
+        selection={ _selection }
+        selectionMode={ SelectionMode.multiple }
+        layoutMode={ DetailsListLayoutMode.fixedColumns }
+        columns={ _columns }
+        onColumnResized={ onColumnResized }
+      />
+    );
+
+    const rootElement = wrapper.getDOMNode();
+    const sizerElement = wrapper.find('[data-sizer-index=0]').getDOMNode();
+    const header: any = headerRef.value;
+
+    // Trigger a mousedown, which validates that the ref to focuszone is hooking up events.
+    EventGroup.raise(
+      sizerElement,
+      'mousedown',
+      {
+        clientX: 0,
+        button: 0
+      },
+      true
+    );
+
+    // Validate we go into resize mode.
+    expect(sizerElement.classList.contains('is-resizing')).toBe(true);
+    expect(!!wrapper.state().isSizing).toBe(false);
+
+    // Mouse move 1 pixel to the right to get into sizing mode.
+    wrapper.simulate('mousemove', { clientX: 1 });
+    expect(!!wrapper.state().isSizing).toBe(true);
+
+    // The header is 200; move mouse 100 to the right, the header should be 300.
+    header._onSizerMouseMove({ clientX: 100 });
+    expect(lastResize).toEqual({ index: 0, size: 300 });
+
+    // Mouse move 300 pixels to the right (should be capped at 400px width
+    header._onSizerMouseMove({ clientX: 300 });
+    expect(lastResize).toEqual({ index: 0, size: 400 });
+
+    // Complete sizing.
+    header._onSizerMouseUp();
+    expect(!!wrapper.state().isSizing).toBe(false);
+  });
+});
\ No newline at end of file
diff --git a/packages/office-ui-fabric-react/src/components/DetailsList/DetailsHeader.tsx b/packages/office-ui-fabric-react/src/components/DetailsList/DetailsHeader.tsx
index 66fac2d89edb4..90fc0e3968904 100644
--- a/packages/office-ui-fabric-react/src/components/DetailsList/DetailsHeader.tsx
+++ b/packages/office-ui-fabric-react/src/components/DetailsList/DetailsHeader.tsx
@@ -1,4 +1,5 @@
 import * as React from 'react';
+import { findDOMNode } from 'react-dom';
 import {
   BaseComponent,
   css,
@@ -9,7 +10,7 @@ import {
   createRef
 } from '../../Utilities';
 import { IColumn, DetailsListLayoutMode, ColumnActionsMode } from './DetailsList.types';
-import { FocusZone, FocusZoneDirection } from '../../FocusZone';
+import { IFocusZone, FocusZone, FocusZoneDirection } from '../../FocusZone';
 import { Icon } from '../../Icon';
 import { Layer } from '../../Layer';
 import { GroupSpacer } from '../GroupedList/GroupSpacer';
@@ -28,7 +29,7 @@ const INNER_PADDING = 16;
 const ISPADDED_WIDTH = 24;
 
 export interface IDetailsHeader {
-  focus(): boolean;
+  focus: () => boolean;
 }
 
 export interface IDetailsHeaderProps extends React.Props<DetailsHeader> {
@@ -81,7 +82,7 @@ export class DetailsHeader extends BaseComponent<IDetailsHeaderProps, IDetailsHe
     collapseAllVisibility: CollapseAllVisibility.visible
   };
 
-  private _root = createRef<FocusZone>();
+  private _root = createRef<IFocusZone>();
 
   private _id: string;
 
@@ -101,11 +102,8 @@ export class DetailsHeader extends BaseComponent<IDetailsHeaderProps, IDetailsHe
 
   public componentDidMount() {
     const { selection } = this.props;
-    const rootElement = this._root.value;
-
-    if (!rootElement) {
-      return;
-    }
+    const focusZone = this._root.value;
+    const rootElement = findDOMNode(focusZone as any);
 
     this._events.on(selection, SELECTION_CHANGE, this._onSelectionChanged);
 
@@ -516,9 +514,12 @@ export class DetailsHeader extends BaseComponent<IDetailsHeaderProps, IDetailsHe
         movement = -movement;
       }
 
+      const column = columns[columnResizeDetails!.columnIndex];
+      const requestedSize = columnResizeDetails!.columnMinWidth + movement;
+
       onColumnResized(
-        columns[columnResizeDetails!.columnIndex],
-        columnResizeDetails!.columnMinWidth + movement,
+        column,
+        !!column.maxWidth ? Math.min(column.maxWidth, requestedSize) : requestedSize,
         columnResizeDetails!.columnIndex
       );
     }
diff --git a/packages/office-ui-fabric-react/src/components/DetailsList/__snapshots__/DetailsHeader.test.tsx.snap b/packages/office-ui-fabric-react/src/components/DetailsList/__snapshots__/DetailsHeader.test.tsx.snap
new file mode 100644
index 0000000000000..311fa3eb38b37
--- /dev/null
+++ b/packages/office-ui-fabric-react/src/components/DetailsList/__snapshots__/DetailsHeader.test.tsx.snap
@@ -0,0 +1,217 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`DetailsHeader can render 1`] = `
+<div
+  aria-describedby={undefined}
+  aria-label={undefined}
+  aria-labelledby={undefined}
+  className="ms-FocusZone ms-DetailsHeader"
+  data-automationid="DetailsHeader"
+  data-focuszone-id="FocusZone1"
+  onFocus={[Function]}
+  onKeyDown={[Function]}
+  onMouseDownCapture={[Function]}
+  onMouseMove={[Function]}
+  role="row"
+>
+  <div
+    aria-colindex={0}
+    aria-labelledby="header0-check"
+    className="ms-DetailsHeader-cell ms-DetailsHeader-cellIsCheck"
+    onClick={[Function]}
+    role="columnheader"
+  >
+    <span
+      className=""
+    >
+      <div
+        aria-checked={undefined}
+        aria-describedby="header0-checkTooltip"
+        aria-label={undefined}
+        className="ms-DetailsRow-check ms-DetailsRow-check--isHeader undefined"
+        data-automationid="DetailsRowCheck"
+        data-is-focusable={true}
+        data-selection-toggle={true}
+        id="header0-check"
+        role="checkbox"
+      >
+        <div
+          className=
+              ms-Check
+              {
+                height: 18px;
+                line-height: 1;
+                position: relative;
+                user-select: none;
+                vertical-align: top;
+                width: 18px;
+              }
+              &:before {
+                background: #ffffff;
+                border-radius: 50%;
+                bottom: 1px;
+                content: "";
+                left: 1px;
+                opacity: 1;
+                position: absolute;
+                right: 1px;
+                top: 1px;
+              }
+              .checkHost:hover &, .checkHost:focus &, &:hover, &:focus {
+                opacity: 1;
+              }
+        >
+          <i
+            aria-hidden={true}
+            className=
+                ms-Check-circle
+                {
+                  display: inline-block;
+                }
+                {
+                  color: #c8c8c8;
+                  font-size: 18px;
+                  height: 18px;
+                  left: 0px;
+                  position: absolute;
+                  text-align: center;
+                  top: 0px;
+                  vertical-align: middle;
+                  width: 18px;
+                }
+                @media screen and (-ms-high-contrast: active){& {
+                  color: WindowText;
+                }
+            data-icon-name="CircleRing"
+            role="presentation"
+          />
+          <i
+            aria-hidden={true}
+            className=
+                ms-Check-check
+                {
+                  display: inline-block;
+                }
+                {
+                  color: #c8c8c8;
+                  font-size: 16px;
+                  height: 18px;
+                  left: .5px;
+                  opacity: 0;
+                  position: absolute;
+                  text-align: center;
+                  top: 0px;
+                  vertical-align: middle;
+                  width: 18px;
+                }
+                &:hover {
+                  opacity: 1;
+                }
+                @media screen and (-ms-high-contrast: active){& {
+                  -ms-high-contrast-adjust: none;
+                }
+            data-icon-name="StatusCircleCheckmark"
+            role="presentation"
+          />
+        </div>
+      </div>
+    </span>
+  </div>
+  <div
+    aria-colindex={1}
+    aria-disabled={false}
+    aria-sort="none"
+    className="ms-DetailsHeader-cell is-actionable undefined"
+    data-automationid="ColumnsHeaderColumn"
+    data-item-key="a"
+    role="columnheader"
+    style={
+      Object {
+        "width": 216,
+      }
+    }
+  >
+    <span
+      className=""
+    >
+      <span
+        aria-describedby="header0-a-tooltip"
+        aria-haspopup={false}
+        aria-label={undefined}
+        aria-labelledby="header0-a-name "
+        className="ms-DetailsHeader-cellTitle"
+        data-is-focusable={true}
+        id="header0-a"
+        onClick={[Function]}
+        onContextMenu={[Function]}
+        role="button"
+      >
+        <span
+          className="ms-DetailsHeader-cellName"
+          id="header0-a-name"
+        >
+          a
+        </span>
+      </span>
+    </span>
+  </div>
+  <div
+    aria-hidden={true}
+    className="ms-DetailsHeader-cellSizer"
+    data-is-focusable={false}
+    data-sizer-index={0}
+    onBlur={[Function]}
+    onClick={[Function]}
+    onDoubleClick={[Function]}
+    role="button"
+  />
+  <div
+    aria-colindex={2}
+    aria-disabled={false}
+    aria-sort="none"
+    className="ms-DetailsHeader-cell is-actionable undefined"
+    data-automationid="ColumnsHeaderColumn"
+    data-item-key="b"
+    role="columnheader"
+    style={
+      Object {
+        "width": 216,
+      }
+    }
+  >
+    <span
+      className=""
+    >
+      <span
+        aria-describedby="header0-b-tooltip"
+        aria-haspopup={false}
+        aria-label={undefined}
+        aria-labelledby="header0-b-name "
+        className="ms-DetailsHeader-cellTitle"
+        data-is-focusable={true}
+        id="header0-b"
+        onClick={[Function]}
+        onContextMenu={[Function]}
+        role="button"
+      >
+        <span
+          className="ms-DetailsHeader-cellName"
+          id="header0-b-name"
+        >
+          b
+        </span>
+      </span>
+    </span>
+  </div>
+  <div
+    aria-hidden={true}
+    className="ms-DetailsHeader-cellSizer"
+    data-is-focusable={false}
+    data-sizer-index={1}
+    onBlur={[Function]}
+    onClick={[Function]}
+    onDoubleClick={[Function]}
+    role="button"
+  />
+</div>
+`;
diff --git a/packages/utilities/src/EventGroup.ts b/packages/utilities/src/EventGroup.ts
index cb8847aece11a..d86af7d05f260 100644
--- a/packages/utilities/src/EventGroup.ts
+++ b/packages/utilities/src/EventGroup.ts
@@ -85,8 +85,9 @@ export class EventGroup {
         let ev = document.createEvent('HTMLEvents');
 
         ev.initEvent(eventName, bubbleEvent || false, true);
-        // tslint:disable-next-line:no-any
-        (ev as any)['args'] = eventArgs;
+
+        Object.assign(ev, eventArgs);
+
         retVal = target.dispatchEvent(ev);
         // tslint:disable-next-line:no-any
       } else if ((document as any)['createEventObject']) { // IE8