Difficulties in communication and social functioning are key diagnostic components of intellectual disability (ID), and negatively impact the wellbeing of those with ID. Communication and social difficulties are multifaceted and comprise a wide breadth of skills. Current approaches in research and intervention often do not include refined assessment of communicative and social functioning in those with ID. Yet, in-depth behavioral phenotyping in neurogenetic syndromes associated with ID indicates that aspects of communication and social functioning are dissociable and interact with one another culminating in a diverse range of unique behavioral profiles between and within these groups. Detailed assessment of such profiles contributes to refined understanding of the developmental mechanisms underlying distinct aspects of communication and social functioning, and thus the advancement of targeted and evidence-based intervention. We discuss insights gained from refined assessment in five neurogenetic syndromes with distinct profiles of social and communication skills: Angelman syndrome, Cornelia de Lange syndrome, Down syndrome, fragile X syndrome and tuberous sclerosis complex. Specifically, we compare findings and the improved knowledge derived from detailed assessments relative to broader measures that mask nuanced strengths and difficulties. We then consider how refined but practical assessment approaches may be applied in research and intervention in broader groups of people with ID with heterogeneous causes.