The aim of this thesis was to understand the life experience and feelings of adults who became aware of their autism diagnosis after 18 years of age. A qualitative research was conducted in which 12 autistic people were interviewed. The results were analyzed according to the content analysis method, using a categorical approach. From the analysis of the material, five categories related to life experience emerged (social difficulties as the main point; sensory issues; language difficulties and naivety; rigidity/repetitive behavior; facilities/advantages that autism brought) and seven categories related to feelings and changes after receiving the diagnosis (alexithymia; relief; revisiting the past; self-compassion; acquired rights, personal identity; social identity). The data from this investigation is organized and detailed in four articles. The first of them, Autism in adults: life experiences after a late diagnosis, explored life narratives, present and past, of this group of people, and it was observed that painful experiences related to social, sensory and language difficulties are common. The second, Autism in adults: feelings and changes after late diagnosis, investigated the feelings and what changed in the lives of those interviewed after the diagnosis, obtaining as a result that relief is a very common sentiment, followed by an understanding of the past and an increase in self-respect. The third article, After all, am I autistic or do I have autism?: identity in focus, sought to understand how this group of adults see their autism, the impact of the diagnosis on the construction of their personal and social identity. The results suggested that it is common to perceive autism as something inseparable from the person s identity, although there is often doubt about communicating the diagnosis socially. Finally, the fourth and final article, Neurodiversity: a new diagnosis?, presented a review and reflection on what neurodiversity is, whether it can be used as a medical diagnosis and how this movement relates to different models of disability.