This study examined a model of assessment that could be applied nationally for Year Twelve Vocational Education and Training (VET) subjects and which could yield both a differentiating score and recognition of competence. More than fifty colleges across all states and territories of Australia field-tested the approach over one school year. Results showed that the model allowed for a standards-referenced model to be used: that the approach was compatible with the diverse range of senior secondary assessment systems in use throughout Australia and that there were considerable cost benefits to be had in adopting the logic of item response modelling for the development of rubrics for scoring performances on units of competence from National Training Packages. A change in the logic of competency assessment was proposed, in that the performance indicators were not rated using a dichotomy but with a series of quality ordered criteria to indicate how well students performed specified tasks in the workplace or its simulation. The study validated the method of assessment development, demonstrated the method's consistency, and showed how the method could address the issue of consistency across states. The study also proposed a set of principles for a joint assessment of both quality and competence. (Contains 5 figures and 3 tables.)