LispWorks has been developed continuously since 1987. The originator company was Harlequin, and the subsequent owners have been Global Graphics, Xanalys, and now LispWorks Ltd. Despite the changes of ownership, the core development team dating back to the early days at Harlequin is still working on the product in 2015 and is still based in Cambridge, England.
Technically, LispWorks's distant origins include Spice Lisp, while the the editor began life as a branch of Hemlock, and the CLOS implementation started out as a branch of PCL (Portable Common Loops).
CLtL and CLtL2 were the reference works until 1994 when the ANSI Common Lisp standard was finalized, making Common Lisp the first formally standardized object-oriented language. The LispWorks team worked hard towards ANSI conformance.
In 1996 LispWorks for Windows was released, with affordable licensing bringing the product to a wider audience. A three-level licensing model was introduced including the free Personal Edition for non-commercial use. With a goal of making LispWorks the most popular and accessible Lisp IDE, ports to Linux (1999) and Mac OS X (2003) followed.
LispWorks 5.0 was released in 2006 with a new 64-bit implementation, an overhaul of the 32-bit architecture on x86 platforms, and a new FreeBSD port.
In 2008 LispWorks 5.1 followed with IDE improvements and wider support for dynamic libraries.
LispWorks 6.0 was released in 2010, including extensive support for SMP, a new x86/x64 Solaris port and a new GTK+ GUI as a modern alternative to Motif.
In 2012 LispWorks 6.1 followed, adding environment access, high-quality drawing including anti-aliasing, export of various image formats, SMP extensions and a 64-bit FreeBSD port.
Of the LispWorks add-on modules, KnowledgeWorks is the oldest, dating back to 1990. Common SQL dates back to 1992 (with most of the current API). There was an earlier SQL interface, but the API was different. The LispWorks CLIM 2.0 implementation was first released in 1997. LispWorks ORB dates back to 1997.
We would be delighted to hear from developers and users of LispWorks over the years who can improve this brief history.
Here's a general History of LISP.