LispWorks supports threads for running computations in parallel. The programming environment, for example, makes extensive use of this mechanism to create separate threads for the various tools.
On Microsoft Windows, Mac OS X, Linux, x86/x64 Solaris and FreeBSD, LispWorks multiprocessing uses native threads and supports Symmetric Multiprocessing (SMP). The implementation is referred to as "SMP LispWorks" where relevant.
On other platforms LispWorks uses a single native thread and implements user level threads. The implementation is referred to as "non-SMP LispWorks" where relevant.
In SMP LispWorks, Lisp processes (as reported by the Lisp function ps) are Operating System threads. These do not necessarily correspond to what system tools show you, for example in Microsoft Windows the Activity monitor shows OS processes, including exactly one for each running LispWorks image.
LispWorks User Guide and Reference Manual - 13 Feb 2015