This paper presents theoretical woric that builds a suite of metrics for object-oriented design.In particular, these metrics are based upon measurement theory and are also informed by the insights of experienced object-oriented software developers. In evaluating these metrics against a standard set of criteria, they are found to both (a) perform relatively well, and (b) suggest some ways in which Lhe object oriented approach may differ in terms of desirable or necessary design features from more traditional approaches.In order for object-oriented software production to fulfill its promise in moving software development and maintenance from the current 'craft' environment into something more closely resembling conventional engineering, it will require metrics of the process to aid the software management, project planning and project evaluation functions. While software metrics are a generally desirable feature in any software environment, they are of special imponance in the object-oriented approach, since it represents a non-trivial technological change for the organization.The metrics presented in this paper are the first steps in a project aimed at measuring and evaluating the use of object oriented design principles in organizations.