The aim of the present study was to design an objective task to assess persistence as a personality variable. The conditions for assessing behavioral persistence were analyzed according to the concepts of motivational persistence, obstinate persistence and exploratory persistence. A free operant procedure with an acquisition and an extinction phase was used as a possible context for assessing persistence. The results show that the designed task enabled the measurement of the three variables of persistence in the sample studied. Internal consistency indexes were .928 for motivational persistence, .683 and .580 for the two indicators of obstinate persistence, and .905 for exploratory persistence. The relationships between each persistence variable and the initial motivation of the participants are consistent with those described in the literature.