The Implicit Association Test (IAT, Greenwald, McGhee, & Schwartz, 1998) was adapted to assess the automatically activated (implicit) self‐concept of aggressiveness. In three studies the validity of the Aggressiveness‐IAT (Agg‐IAT) was supported by substantial correlations with self‐report measures of aggressiveness. After controlling for self‐report measures of aggressiveness, the Agg‐IAT accounted for 9–15% of the variance of three different indicators of aggressive behavior across three studies. To further explore the nomological network around the Agg‐IAT we investigated its correlations with measures of social desirability (SD). Although not fully conclusive, the results across four studies provided some support for a weak negative correlation between impression management SD and aggressive behavior as well as the Agg‐IAT. This result is in line with an interpersonally oriented self‐control account of impression management SD. Individuals with high SD scores seem to behave less aggressively, and to show lower Agg‐IAT scores. The one‐week stability of the Agg‐IAT was r = .58 in Study 4. Aggr. Behav. 9999:XX–XX, 2014. © 2014 Wiley Periodicals, Inc.