All but two of the states are in the process of implementing some form of mandatory teacher testing, if they have not already done so. However, the limitations of state procedures, i.e., different standards, approaches, and requirements, combined with significant improvement in evaluation techniques, have led to the call for a system of national assessment. This Digest discusses what national teacher certification will mean and what it will consist of. The potential effect on teachers of national assessment and certification is considered. Citations from the ERIC database are included. (JD)