This collection of papers draws together a variety of approaches for adding ob­ ject orientation to the Z formal specification language. These papers are not a conference proceedings, but have a slightly more complicated his tory. This work has grown and evolved from some work originally done in the ZIP project, under the United Kingdom's Department of Trade and Industry (DTI) IED initiative. ZIP is a three year project which aims to make the use of the Z specification language more widespread. It hopes to achieve this by producing a standard for Zj developing a method for Zj building tool support for Zj and carrying out research into refinement, proof and concurrency in Z. The ZIP methods work includes performing a survey of current Z practitioners (reported in [Barden et al. 1992])j investigating current styles and methods of Z usagej and developing a Z Method handbook (available early in 1993). As part of this work, we carried out a comparative study of the ways in which object orientation has been combined with Z. A summary of that work has been published as [Stepney et al. 1992].