as mentionedthe os fork call is present in the cygwin version of python on windows even though this call is missing in the standard version of python for windowsyou can fork processes on windows with python if you install and use cygwin howeverthe cygwin fork call is not as efficient and does not work exactly the same as fork on true unix systems cygwin is freeopen source package which includes library that attempts to provide unix-like api for use on windows machinesalong with set of command-line tools that implement unix-like environment it makes it easier to apply unix skills and code on windows computers according to its faq documentationthough"cygwin fork(essentially works like noncopy on write version of fork((like old unix versions used to dobecause of this it can be little slow in most casesyou are better off using the spawn family of calls if possible since this book' fork examples don' need to care about performancecygwin' fork suffices in addition to the fork callcygwin provides other unix tools that would otherwise not be available on all flavors of windowsincluding os mkfifo (discussed later in this it also comes with gcc compiler environment for building extensions for python on windows that will be familiar to unix developers as long as you're willing to use cygwin libraries to build your application and power your pythonit' very close to unix on windows like all third-party librariesthoughcygwin adds an extra dependency to your systems perhaps more criticallycygwin currently uses the gnu gpl licensewhich adds distribution requirements beyond those of standard python unlike using python itselfshipping program that uses cygwin libraries may require that your program' source code be made freely available (though redhat offers "buy-outoption which can relieve you of this requirementnote that this is complex legal issueand you should study cygwin' license on your own if this may impact your programs its license doeshoweverimpose more constraints than python' (python uses "bsd"-style licensenot the gpldespite licensing issuecygwin still can be great way to get unix-like functionality on windows without installing completely different operating system such as linux-- more complete but generally more complex option for more detailssee see also the standard library' multiprocessing module and os spawn family of callscovered later in this for alternative way to start parallel tasks and programs on unix and windows that do not require fork and exec calls to run simple function call in parallel on windows (rather than on an external program)also see the section on standard library threads later in this threadsmultiprocessingand os spawn calls work on windows in standard python forking processes