["Journal of Child Psychology and Psychiatry, EarlyView. ", "\n\nBackground\nCallous‐unemotional (CU) traits in early childhood are risk markers for persistent antisocial behaviour, with marked adverse life outcomes. However, associations of CU traits with broader psychosocial characteristics are not well understood, particularly in early childhood.\n\n\nObjective\nTo examine developmental and psychosocial profiles of pre‐school children according to their levels of CU traits and conduct problems (CPs) in a large, population‐based cohort from southern Brazil.\n\n\nMethods\nThe 2015 Pelotas Birth Cohort includes 4,275 children followed from birth. At age 4 years, CU traits and CP were assessed via parent‐report questionnaires, and 19 other psychosocial characteristics were examined mostly in task‐based assessments regarding: neurodevelopment, language, executive functioning, emotion recognition, theory of mind, social information processing and empathy/prosocial behaviours. These 19 psychosocial characteristics were compared across four groups of children with varying levels of CU/CP, and regression models were used to test for independent associations with CU traits and CP, adjusting for sociodemographic factors at birth.\n\n\nResults\nAt age 4 years, 14.8% of children had elevated CU traits only, 14.2% had CP only, and 16.3% had both high CU + CP. Compared to children without CU traits or CP, children with higher CU traits had poorer performance across multiple domains of development, including language, motor development, emotion recognition and prosocial behaviour. In contrast, children with CP‐only showed more circumscribed deficits, mainly in self‐control and emotional functioning. In regression analyses, CU traits were associated with broader neurodevelopmental impairments, whereas CP was more specifically linked to behaviour regulation.\n\n\nConclusions\nElevated CU traits in early childhood are associated with broad developmental difficulties, whereas CPs relate more specifically to emotional and self‐regulation challenges. These findings underscore the need for holistic approaches to understanding early manifestations of CU traits and interventions in the context of CP behaviours.\n\n"]