This study investigated the beliefs about additional language learning and use and knowledge of additional languages of 226 multilingual adults with Attention-deficit/hyperactivity disorder (ADHD) with Polish L1. The data were collected via an online questionnaire with Likert-type statements. Data were analyzed using mixed models (GLMMs). The findings show that a) individuals with ADHD hold a neutral view of their additional language learning and use experiences; b) the hyperactivity/impulsivity ADHD presentation may positively affect additional language learning; and c) Autism spectrum disorder (ASD) or dyslexia has no impact on additional language knowledge in the context of ADHD. The discussion points to the importance of attention in additional language acquisition and the possible compensatory role of ADHD and ASD in the context of dyslexia and language learning.
