The revised reinforcement sensitivity theory-personality questionnaire (RST-PQ), developed by Corr and Cooper, is a new questionnaire that corresponds with the revised version of the reinforcement sensitivity theory. The aim of this article is to present an extended analysis of the construct validity of RST-PQ's Polish adaptation. Two studies were conducted: the first was to establish construct validity, and the second to test stability over a five-week period. The results showed that the internal consistency of all the scales is satisfactory, comparable to or even higher than for the original version. Examining construct validity with other personality measures (EPQ-R, STAI, BIS/BAS, SPSRQ-s, PANAS-X, FCB-TI) showed that the Polish version of the RST provides an adequate measure of the theoretical constructs differentiated in the revised RST. Moreover, the results showed that RST-PQ is a sensitive measure that makes it possible to accurately detect clinical form of depression. The factor structure of the Polish version generally replicated the original one, albeit with slightly weaker parameters. Test-retest reliability was found to be generally acceptable.