The Adult Eating Behavior Questionnaire (AEBQ) is a tool developed in the UK, used in the investigation of appetitive traits in adults and adolescents, and later validated in a number of countries. To date, the validity of the AEBQ has not been tested on Portuguese-speaking popula-tions. The aim of this study was to validate the AEBQ in a sample of Portuguese adolescents. Participants were 4483 13-year-olds enrolled in the population-based cohort study Generation XXI. Appetitive traits were self-reported by adolescents through the AEBQ and parents also reported adolescent eating behaviors. Confirmatory and exploratory factor analyses were conducted. Construct validity was tested through correlations between AEBQ subscales and parent-reported eating behaviors, and linear regressions between AEBQ subscales and adolescent body mass index z-scores were performed. Adequate internal consistency and several associations with parent-reported eating behaviors and measured adolescent body mass index z-scores were found. This study supports the validity of a five-factor AEBQ (Food Responsiveness and Enjoyment of Food; Slowness in Eating; Food Fussiness; Emotional Over- and Undereating) to measure appetitive traits among Portuguese adolescents and provides a convenient and easy-to-use tool to be used in large-scale research.