1 Département de Psychopédagogie Et d'andragogie, Université de Montréal, 90, Avenue Vincent-d'Indy, Montréal, QC, H2V 2S9, Canada. elizabeth.olivier@umontreal.ca.
2 Substantive-Methodological Synergy Research Laboratory, Department of Psychology, Concordia University, Montreal, QC, Canada.
3 Cyberpsychology Laboratory, Department of Psychoeducation and Psychology, Université du Québec en Outaouais (UQO Campus de Saint-Jérôme), Saint-Jérome, QC, Canada.
4 School of Education, Translational Health Research Institute, Western Sydney University, Sydney, Australia.
5 Institute for Positive Psychology and Education, Australian Catholic University, Sydney, Australia.

This study sought to identify the various configurations, or profiles, of internalizing and externalizing behaviors found among a sample of youth with intellectual disabilities (ID). These behaviors were assessed twice over one year, using self, parental, and teacher reports. Six variables were hypothesized to predict profile membership: Parent-child relationship (i.e., warmth and conflict), student-teacher relationship (i.e., warmth and conflict), peer acceptance, and peer victimization. To this end, we conducted Latent Profile Analysis among a sample of 393 youth with ID (aged 11-22 years old) recruited in Canada (French-speaking; n = 142; 49.30% boys) and Australia (English-speaking; n = 251; 67.30% boys). Our results revealed five profiles: (1) Adjusted (13.48%), (2) Mild School-related Difficulties (34.38%), (3) Underestimation of Mild Difficulties (12.40%), (4) High Difficulties (19.45%), and (5) Internalizing Difficulties Unobserved at School (20.19%). These profiles, as well as profile membership, remained stable over time. Lower levels of student-teacher warmth, lower levels of peer acceptance, and higher levels of peer victimization were associated with a higher likelihood of membership into profiles characterized by above-average levels of psychosocial difficulties, especially self-reported. Based on these findings, future interventions addressing internalizing and externalizing behaviors could benefit from focusing on the school environment, notably peer acceptance and student-teacher warmth.