The VAX security kernel, a prototype security kernel implemented as a virtual machine monitor (VMM) for the VAX architecture, is capable of emulating one or more virtual machines (VMs) on a single physical machine allowing multiple copies of virtual machine operating systems to execute concurrently. The system supports both VMS and ULTRIX as virtual machine operating systems. A fundamental component of any security kernel is the ability to produce an audit trial of security relevant events. While there are numerous examples of auditing subsystems at the DoD Trusted Computer System Evaluation Criteria (TCSEC) C2 or B1 level, there is much less experience with the requirements at the B2 level and above. The design and implementation of the VAX security kernel auditing facility, built to satisfy the requirements at the A1 level, are described.>