Nine studies were conducted with the goal of developing a self-report measure of psychological entitlement and assessing its interpersonal consequences. The Psychological Entitlement Scale (PES) was found to be reliable and valid (Study 1, 2), not associated with social desirability (Study 2), stable across time (Study 3), and correlated negatively with two of the Big Five factors: agreeableness and emotional stability (Study 4). The validity of the PES was confirmed in studies that assessed willingness to take candy designated for children (Study 5) and reported deservingness of pay in a hypothetical employment setting (Study 6). Finally, the PES was linked to important interpersonal consequences including competitive choices in a commons dilemma (Study 7), selfish approaches to romantic relationships (Study 8), and aggression following ego threat (Study 9). Psychological entitlement has a pervasive and largely unconstructive impact on social behavior.