(1) Introductory implementation : Change in development objective from defect correction to defect prevention in specification, design and verification. Developers have been conditioned to write code which would inevitably contain errors. A psychological change is required, from expecting errors to expecting correctness. This is achieved only through experience, and developers begin to realize that Cleanroom code is of such high quality that little debugging is required.

Small teams perform testing and development under the supervision of management who ensure that there is no deviation from the fundamental Cleanroom principles since any compromise in process inevitably leads to compromise in quality.

Maintaining customer involvement is also vital - producing a zero-defect product is pointless if it does not comply to the customer's requirements.

In the design process, state and clear box concepts are implemented. One goal of this process is the design simplification - this makes the job of correctness verification and subsequent maintenance easier.

All designs and specifications undergo vigorous team-based correctness verification. This provides team members with a better understanding of designs and their validity.
Usage testing based on external system behavior replaces coverage testing based on design internals.

At this point, effectiveness of the development process is evaluated. The test results are compared with predetermined quality standards and if the results show that the development process is not meeting quality objectives, the development and verification process is repeated.