We establish whether the efficacy of mutual monitoring in fostering cooperation is dependent on the degree of approval motivation within teams. Approval motivation is defined as the desire to produce positive perceptions in others and the incentive to acquire the approval of others as well as the desire to avoid disapproval, (Martin in J Personality Assess 48(5):508–519, 1984). Contrary to the theoretical predictions, the results from the experiment suggest that mutual monitoring was not effective in fostering cooperation in teams. Furthermore, the efficacy of mutual monitoring in fostering cooperation was not correlated with the degree of approval motivation within teams.