The Windows 3.x family of Microsoft Windows operating systems were released from 1990 to 1994. The 3.0 release was the first widely successful version of Windows (see history of Microsoft Windows), enabling Microsoft to compete with Apple Computer's Macintosh and the Commodore Amiga on the GUI front.

Windows 3.0 was released on May 22, 1990 and included a significantly revamped user interface as well as technical improvements to make use of the memory management capabilities of Intel's 80286 and 80386 processors. Text-mode programs written for MS-DOS could be run within a window, making the system usable as a crude multitasking base for legacy programs, though this was of limited use for the home market, where most games and entertainment programs continued to require raw DOS access.

The MS-DOS Executive file manager/program launcher was replaced with an icon-based Program Manager and a list-based File Manager called Winfile, thereby simplifying the launching of applications. A Control Panel, modeled after that of MacOS, centralized system settings, including limited control over the color scheme of the interface. A number of simple applications were included, such as a text editor Notepad and word processor Write, a macro recorder, and a calculator.

Windows 3.1, released on March 18, 1992, added basic multimedia support for audio input and output and a CD audio player application, as well as a TrueType font system (and a set of highly legible fonts already installed) which effectively made Windows a serious desktop publishing platform for the first time.

TCP/IP networking under Windows 3.x relied on third-party packages, such as Trumpet Winsock. Upgrading to Windows for Workgroups, an extended version of Windows 3.11, included SMB file sharing support was another solution.

Limited compatibility with the new 32-bit Win32 API used by Windows NT was provided by an add-on package, Win32s.

Windows 3.2 was a Chinese-language release only.

Windows 3.x was eventually superseded by Windows 95, Windows 98, and later versions which integrated the MS-DOS and Windows components into a single product.

See also History of Microsoft Windows.