The purposes of the paper were to develop a structure by which assessment models could be uniquely characterized and to develop assessment models and their associated computer programs which could be used for personnel research purposes. To these ends two aspects of assessment, measurement and evaluation, were identified. Their distinction was mainly in the process used to respond to the items of an assessment instrument. The parameters of the assessment models were identified. These were variously combined and operationalized into either measurement or evaluation models. The intention of this process was to make evaluation more measurement-like by using and developing evaluation models, for polychotomous response information, which were patterned after Rasch latent-trait measurement models. Also developed were some special models for use in decision making paradigms and for assessment situations for which an estimation sample does or does not exist. Analysis of these models and their associated data were provided by a system of computer programs called PRIME. In all, five programs were developed, illustrated, and documented. Applications of these models and computer programs to personnel research areas of the Navy Personnel Research and Development Center research program was discussed. (RC)