Neurofibromatosis type 1 (NF1) is a genetic syndrome affecting about 1 in 3500 individuals; many of those affected have plexiform neurofibroma (pNF) tumors and associated symptoms and complications. Furthermore, learning and attention problems, as well as deficits in adaptive functioning, are common, often beginning in early childhood. This study aimed to describe adaptive functioning and to examine relationships between adaptive functioning and cognitive and academic variables and level of independence among adolescents and young adults (AYA) with NF1 and pNF tumors. Fifty-five AYA aged 16-31 years participated in a series of neuropsychological evaluations while parents completed the Vineland Adaptive Behavior Scales (VABS-II) as part of a larger natural history study. Over one-third (35%) of AYA were neither in school nor employed. Mean VABS-II daily living and socialization scores were low average while mean Verbal and Performance IQ scores were average. VABS-II scores were positively correlated with processing speed, executive functioning, and working memory scores. Verbal IQ was the only significant predictor of work/school status. Identification of the correlates and predictors of adaptive functioning and life achievement can help guide healthcare providers with the early identification of risk factors and possible areas for intervention. K E Y W O R D S adaptive functioning, adolescents and young adults (AYA), NF1 1 | INTRODUCTION Research suggests that early adaptive skills in young children with neurofibromatosis type 1 (NF1) are lower than same-aged peers (Klein-Tasman et al, 2013). Adaptive behavior is commonly defined as how people meet their daily needs and navigate the expectations in their day-to-day interactions. Areas of adaptive functioning include communication, daily living skills, and socialization (Sparrow, Cicchetti, & Balla, 2005). For individuals diagnosed with NF1, these deficits continue (Cohen et al., 2020;Payne et al., 2021) and in one study worsen (Glad et al., 2020) throughout childhood and adolescence. These deficits have even been documented in the context of average cognitive abilities (Eby, Griffith, Gutmann, & Morris, 2019). Glad et al. (2020) found executive functioning in early childhood to be predictive of adaptive functioning in the school-age period.NF1 is a genetic disorder that occurs in approximately 1 out of every 2500-3500 births and is typically diagnosed in early childhood (Evans et al., 2010;Tonsgard, 2006). NF1 causes a wide variety of physical, psychosocial, and cognitive impairments, all of which may contribute to challenges in adaptive functioning, particularly during the years of transition from adolescence to young adulthood. Physical [Correction added on 24 December 2021, after first online publication: The blinded text has been replaced with "National Cancer Institute" at all occurrences in the article.]