The aim of the article was to elaborate on a broad construct of work behavior and to develop an instrument to measure one of its three types — extrarole behavior. Final 12­item scale covered three dimensions of extra-role actions. They are: perfection of performance, overtime performance and helping one's colleagues. In addition a 4-item scale of work efficiency was developed to measure dimensions of quality of work and productivity of work. Reliability coefficients of scales were 0.84 and 0.76 respectively. Confirmatory factor analysis showed satisfactory fit of both scales factor structures to empirical data. Construct validation demonstrated that both scales had acceptable construct validity. The possibilities of both scales to be used in future empirical studies are being discussed.