Abstract: Metrics (quantitative estimates of product and project properties) can, if defined from sound engineering principles, be a precious tool for both project management and software development. We have recently developed an extensive set of metrics facilities for the EiffelStudio development environment. We will describe the principles on which it is based, the facilities it provides, and how to use them. The metrics workbench is closely integrated with the rest of the environment. Among other capabilities, it allows users to: apply predefined metrics to components of a system at various levels (feature, class, cluster, entire system); define new metrics, through mathematical formulae or boolean selection, and apply them to projects; store measurement results, as well as metric definitions, into an XML archive that can be stored locally or made available on the Web for future reference; compare the measurements on a system to those on record locally or on a Web site. ISE has released on its own site an archive recording the metric properties of its basic libraries, available to any other project for comparison.