The following new USER functions have been added to Windows 3.1:
| Function | Description |
| CallNextHookEx | Passes hook information down the hook chain. |
| CopyCursor | Copies a cursor. |
| CopyIcon | Copies an icon. |
| EnableCommNotification | Enables or disables WM_COMMNOTIFY posting to window. |
| EnableScrollBar | Enables or disables scroll-bar arrows. |
| GetClipCursor | Retrieves cursor-confining rectangle coordinates. |
| GetCursor | Returns the current cursor handle. |
| GetDCEx | Retrieves the handle of a device context. |
| GetFreeSystemResources | Returns the percentage of free system resource space. |
| GetMessageExtraInfo | Retrieves information about a hardware message. |
| GetOpenClipboardWindow | Returns a handle of the window that currently has the clipboard open. |
| GetQueueStatus | Determines the queued message type. |
| GetSystemDebugState | Returns system-state information to a debugger. |
| GetTimerResolution | Retrieves the timer resolution. |
| GetWindowPlacement | Retrieves the show state and the normal (restored), minimized, and maximized positions of a window. |
| hardware_event | Places a hardware message in the system queue. |
| IsMenu | Determines whether a menu handle is valid. |
| LockInput | Locks input to all tasks except the current one. |
| LockWindowUpdate | Disables or reenables drawing in a window. |
| MapWindowPoints | Converts points to another coordinate system. |
| QuerySendMessage | Determines whether a message originated within a task. |
| RedrawWindow | Updates a client rectangle or region. |
| ScrollWindowEx | Scrolls a window's client area. |
| SetWindowPlacement | Sets the show state and the normal (restored), minimized, and maximized positions of a window. |
| SetWindowsHookEx | Installs a hook function into a hook chain. |
| SubtractRect | Creates a rectangle from the difference between two rectangles. |
| SystemParametersInfo | Queries or sets systemwide parameters. |
| UnhookWindowsHookEx | Removes a function from the hook chain. |
| WNetAddConnection | Adds network connections. |
| WNetCancelConnection | Removes network connections. |
| WNetGetConnection | Lists network connections. |