A general framework for the specification, assessment and acceptance of the human factors aspects of computer based systems is presented. It takes as its origin eight Technical Areas (TAs) derived from the human factors domains. Associated with each TA is a set of Technical Issues (TIs) and models which can be used to structure them and derive tests and criteria for assessment purposes. The TIs can be used to generate requirements statements and hence agreed characteristics which may be used for the definition of tests and testing procedures. An example is provided to show how one might derive TIs and hence requirements statements and acceptance tests to ensure that there is an effective human factors contribution to the procurement process for computer supported systems.