https://doi.org/10.1177/0306624X18811595 International Journal of Offender Therapy and Comparative Criminology 2019, Vol. 63(6) 837–853 © The Author(s) 2018 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0306624X18811595 journals.sagepub.com/home/ijo Article The Adapted Self-Report Delinquency Scale for Adolescents: Validity and Reliability Among Portuguese Youths Pedro Pechorro 1 , Stephen Houghton 2 , Mário R. Simões 3 , and Annemaree Carroll 4 Abstract Self-report delinquency scales have contributed greatly to the contemporary basis of our understanding of juvenile delinquency. Nevertheless, they have not been immune to criticism and further improvement and extensive measurement research is still necessary. The present study examined the psychometric properties of one such measure of self-reported delinquency, the Adapted Self-Report Delinquency Scale (ASRDS). The ASRDS was administered to a Portuguese sample of male youths (N = 470, 12-20 years of age), subdivided into a forensic sample (n = 217) and a school sample (n = 253). The Portuguese version of the ASRDS demonstrated satisfactory psychometric properties, in terms of its factor structure, internal consistency, convergent validity, discriminant validity, criterion-related validity, and known-groups validity, thereby justifying its use among this population. Keywords assessment, crime, self-report delinquency, validation, youth 1 University of Minho, Braga, Portugal 2 The University of Western Australia, Perth, Australia 3 University of Coimbra, Portugal 4 University of Queensland, Brisbane, Australia Corresponding Author: Pedro Pechorro, School of Psychology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal. Email: ppechorro@gmail.com 811595IJO XX X 10.1177/0306624X18811595International Journal of Offender Therapy and Comparative CriminologyPechorro et al. research-article 2018