A study was conducted to review the concept of validity in the context of vocational education and training (VET) in Australia. The study included a review of literature, case studies, presentation of key findings, and recommendation of a tool to guide assessors. An eight-faceted approach to validity, based on Nitko, was developed, with each approach using different kinds of evidence (content, internal coherence, external coherence, reliability, practicality, generalizability, consequential) that may be appropriate within a competency-based approach to assessment. The study showed that the eight types of evidence were, with a single exception (consequential evidence), regarded as important by the study participants. The study finds that the approach to validity indicated by Nitko can be fruitful in improving competency-based assessments. Other findings include the following: (1) some practitioners were reluctant to allow any scrutiny of their assessment practices; (2) records storage and retrieval were sometimes not well-developed; (3) there was no uniform definition of "recognition of prior learning" or "recognition of current competency"; (4) the use of holistic assessment left questions of validity open; and (5) attitude seems to be a factor in employment and on-the-job success but was beyond the scope of the study. A revised definition of validity was proposed that sees validity as "the extent to which the interpretation and use of an assessment outcome can be supported by evidence." (Contains 30 references.) (KC)