ABSTRACT Purpose This study aimed to present findings on language, behavior, and neurodevelopment in a girl diagnosed with Angelman Syndrome, evaluated when she was three and eight years old. Methods The following evaluation instruments were used: Observation of Communication Behavior, Early Language Milestone (ELM) Scale, and Denver Developmental Screening Test, 2nd edition (DDST-II). Results In this case report, presence of AS phenotype signals such as wide mouth and wide-spaced teeth, tongue thrusting, strabismus, up slanting palpebral fissures, and sialorrhea are verified. Expressive and receptive deficits were verified in the language assessment, with the absence of orality and loss of comprehension with very similar performances in both evaluations. The ELM and DDST-II tests indicated severe impairment of all abilities evaluated at both three and eight years of age. Performance was quite similar in both evaluations in all areas of child development. Little progress was observed over time despite the great therapeutic and educational investment. Conclusion The presence of a complex scenario such as AS demands high complexity clinical needs, a situation that is worsened due to scarcity of therapeutic resources that could minimize the harmful impacts of AS and culminate in increased quality of life for the AS population and their families.