The study confirmed that when self-serving mindsets (cognitions) were unusually dominant, externalizing behaviors were also prevalent; and when self-debasing cognitions were dominant, internalizing behaviors were prevalent. Further, in the domain of externalizing behavior, self-serving cognitions with overt behavioral links involved aggressive behavior, and self-serving cognitions linked to covert behavioral referents were linked to delinquent behavior. More specifically, self-serving cognitions with an aggression content resulting in opposition-defiance behavior were related to verbal aggression; whereas self-serving cognitions with a content of physical aggression were related to physically aggressive behavior. The fact of differing cognitions being related to differing types of problematic behavior and emotional states suggests the need for cognitive-behavioral therapies that target different mindsets and perceptions. Also, since specific types of externalizing behaviors are linked to mindset content, this suggests tailoring therapy to this specific content of attitudes/perceptions. Study participants were 239 boys ages 10-19 from schools on the island of Curacao. Their cognitive postures were determined through self-reports (the Youth Self-report for Ages 11 to 18, the Aggression Questionnaire, the How I Think Questionnaire, and the Children's Negative Cognitive Error Questionnaire). 6 tables and 26 references