The WOrk-reLated Flow inventory (WOLF) measures flow at work, defined as a short-term peak experience characterized by absorption, work enjoyment, and intrinsic work motivation. Results of Study 1 among 7 samples of employees (total N=1346) from different occupational groups offer support for the factorial validity and reliability of the WOLF. Study 2 examined the validity of the WOLF in more detail among some of the samples. Positive correlations between a general flow index and the three flow dimensions confirm the convergent validity of the WOLF. In addition, the findings of Study 2 provide evidence for the construct and predictive validity of the WOLF using five job characteristics as predictors of flow, and other-ratings of performance as outcomes.