Clinical assessment relies on both "construct validity", which focuses on the accuracy of conclusions about a psychological phenomenon drawn from responses to a measure, and "case validity", which focuses on the synthesis of the full range of psychological phenomena pertaining to the concern or question at hand. Whereas construct validity is grounded in understanding causal influences of a distinct phenomenon on responses to various measures and life contexts, case validity encompasses the joint influences of multiple phenomena on individuals' responses. Two sets of distinctions essential to understanding psychological phenomena, hence to understanding construct validity, are (a) implicit and explicit versions of personality constructs and (b) ability and personality as versions of constructs measured by performance tests presenting maximal and typical conditions, respectively. Since both implicit and explicit versions of constructs interface with maximal or typical performance conditions, case validity requires systematic inclusion of these distinctions in assessment protocols. (Contains 4 tables, 1 figure and 6 footnotes.)