Adolescence is a critical period for dissociation, until more effective coping strategies are developed. Dissociate in a chronic manner is likely to interfere with the construction of a cohesive sense of self, and may potentiate later psychopathology. Adolescent Dissociative Experiences Scale/A-DES is yet to be studied in Portugal.

Analyze the psychometric properties of the A-DES 11-item format; compare between nonclinical with psychological disturbed adolescents/PDA; and determine the variables that associate with A-DES.

A sample of nonclinical (n = 69) and PDA (n = 45) aged between 11 to 18 years, 55.3% boys and 44.7% girls, education mean years 8.96 (SD = 2.74), completed the A-DES and the Youth Self Report/YSR.

The A-DES had a very good internal consistency (α = 0.94), presenting significant large correlations with YSR (r = 0.67). Confirmatory factor analysis suggested a 1-factor structure.

The mean scores (2.78 ± 1.82) were equivalent to other countries, and significantly discriminated (t = 6.02; p < 0.001; Cohen's d = 1.12) between the nonclinical (M = 2.06 ± 1.41) and PDA (M = 3.89 ± 1.84).

There were no differences between the sexes, but the younger, less educated, and institutionalized had more dissociative experiences (r = 0.21 to 0.30). Hierarchical multiple regression revealed that only YSR was statistically significant in predicting levels of A-DES (Beta = 0.64; p < 0.001).

The Portuguese A-DES version seems a valid and reliable screening for dissociation amongst adolescents.